I've been taking a look back at the Obama presidency this week, so I thought it'd only be fair to look forward today and lay out the possible outcomes of the presidency of Donald Trump. Now, before I even start, I realize this is largely a fool's errand, for any number of reasons. But that's never stopped me before, and today I intend not to make predictions of what will happen, but rather run the whole gamut of what could conceivably happen. If rampant speculation without a shred of conclusion isn't your cup of tea, then I'd advise just skipping today's column altogether.

Predicting any future president's legacy is impossible, of course, because nobody knows what will happen. Anything can happen in American politics, which is only proven by the fact that Donald Trump is about to be sworn in as president. But more importantly, external events often have more to do with how a president is seen later on than anything anyone could have predicted on Inauguration Day. Nobody thought George W. Bush would largely be remembered as a war president in January of 2001, for instance. External events (whether domestic or foreign) often shape a presidency in ways the campaign never anticipated, in other words. So Trump could be remembered later for something nobody expects right now. I'm sure I'll be reading this column in four years' time and laugh at all the things I got wrong, but so be it.

For now, we can at least explore the possibilities of how he would react and how the nation would see it. This list of possible outcomes is roughly ordered from most optimistic to most pessimistic, just to warn you in advance. And most of them are not mutually exclusive -- some combination of these scenarios might turn out to be what actually happens.

America is made great again

Donald Trump succeeds wildly, and we all get "tired of winning" (as he promised). Hey, it could happen! Trump ushers in a new era of American manufacturing due to his high tariffs, and "Made in the USA" becomes a big selling point for corporate giants. Trade deals are rewritten, jobs flood back to America's shores, wages go up, taxes go down, and the economy booms as a result. Trump holds to his promises that his healthcare plan will be better than Obamacare, and that he won't touch Social Security or Medicare. Trump's blustering swagger on the world stage convinces enemies that he's so crazy there's nothing he might not consider, so the world remains calm (at least where U.S. interests are concerned). Trump is re-elected in a landslide. Like I said, anything's possible, right?

Trump not as bad as Democrats thought

Obviously, I consider this one a lot more likely than that last one. Democrats might actually be pleasantly surprised by Trump's willingness to work with them on some specific issues. Of course, Democrats will be fighting Trump tooth and nail on other issues, but Trump is actually not all that ideological in many areas. Or, at least, "not that big a follower of conservative ideology." If Trump makes the case for issues that Democrats have been fighting for for years, then that might just be what it takes to shame congressional Republicans into getting behind some good ideas. Perhaps this will happen on infrastructure spending, or trade policies, or standing up to corporate malfeasance. Trump, as we've all seen, is fairly politically malleable on a number of issues where Republicans usually tout only one orthodox answer. Of course, Trump and the Democrats won't agree on everything, but in this scenario things turn out to be better than they would have been under, say, President Ted Cruz.

Trump muddles along, insists everything's great

I would consider the likelihood of this one to be quite high, personally. Trump has an infinite capacity to believe that he is making things great. His belief that this is always so trumps (side prediction: we're going to get sick of that verb in the next four years) actual facts and actual reality. The news media will try to point out Trump's mistakes and fumbles, but Trump will insist that it's all "fake news," and that the media can't be trusted -- and tens of millions of Americans will believe him. In this scenario, Trump lurches from issue to issue, making decisions which sometimes turn out well and sometimes make things far worse. If Trump is ever forced to face the fact that things went wrong, he will conveniently blame a cabinet secretary, and fire them. He'll have lots of fun doing so, of course (see: Trump's signature television phrase). He'll insist that he got it right, but that his glorious idea was so badly implemented that things went wrong. Trump struggles with both the extreme conservatives in Congress and with Democrats in the Senate, so little gets done legislatively. Things don't get markedly worse for most Americans, but they also don't get noticeably better.

Economic downturn

A caveat before I start: I've always believed that the business cycle operates not totally independently of politics, but pretty close. The business cycle goes up and it goes down, and most of the time this has very little to do with who is currently in the White House and who is running Congress. There is no magic lever in the Oval Office that speeds up or slows down the economy, in other words. We all tend to either ascribe too much blame or give too much credit to presidents who just happen to be there when things boom or bust in the business world.

Having said that, the business cycle is overdue for a downturn, which will likely happen some time in the next four years. This would have probably also have happened under President Hillary Clinton, I might add. But Trump's going to be the one in the hot seat, so Trump is going to have to be the one who deals with it. If America enters into a recession later this year (or next year, or the next), Trump is going to have a tough time dealing with it. His entire candidacy was to "make America great again," but if the economy goes sour, he's going to get the blame for blowing it. This raises a scary thought -- what will Trump do if economic indicators show a recession and rising unemployment? Will he try to unilaterally fudge the figures? Remember that all the agencies tasked with providing such figures are actually part of the executive branch -- which means they're under Trump's direct control. If statistical reality disagrees with Trump's vision of how he's doing, will he be tempted to tinker with the statistics until he's happy with what the numbers say?

Whether that happens or not, Trump may act increasingly petulant when the economy doesn't just follow his decree that America return to greatness. If the public starts engaging in mass nostalgia for the days of Barack Obama and Trump's approval rating heads south in a big way, there's no telling how he'll react.

Congress pulls Trump's strings

These next two are really exclusionary, although a mix of the two might happen.

Paul Ryan and Mitch McConnell begin passing all their conservative dream agenda. This includes many things that Trump actually campaigned against (like entitlement reform), but Trump is cowed into signing all the bills anyway, after convincing himself that he has always supported the ideas (of course). Ryan and McConnell wisely allow Trump to take all the credit as the price for getting their budgets and other laws signed. Vice President Mike Pence is in on the whole scheme, and personally convinces Trump to go along with whatever congressional Republicans dream up. They allow Trump to pass some of his signature issues (as they're already doing, with the wall), so he has something to brag about, but the nine-tenths of the iceberg glides by underwater with few noticing that Trump refuses to stand up to the Republican congressional leaders in any way. Trump is happy enough tweeting and holding rallies, while his agenda gets almost completely hijacked.

Trump has his way with Congress

The other side of the coin could happen, as well. Donald Trump is already scaring Republicans silly, because all he has to do is disparage them in one tweet, and his legions of followers instantly react. Now, a popular GOP senator might stand up to such treatment, but House members are a lot more vulnerable. Paul Ryan and Mitch McConnell might actually be stunned by Trump quashing some of their agenda, on the grounds that he campaigned against such things. Trump might tweet: "No, we're not going to cut Social Security. Bad idea." which would dash Ryan's hopes of doing so, just to give one example.

Trump then proves to be exactly what he always billed himself as: a dealmaker. He listens to what Democrats want, listens to what Republicans want, and then offers both sides a deal with some of column A and some of column B and some of his own agenda thrown in for good measure. This way, Trump gets enough Democratic support in the Senate and enough Republican support in the House to get his compromise deals through Congress. Remember, Trump is only concerned with how Donald Trump is perceived -- meaning he could throw the congressional Republican leadership over the side at any time, if he thinks doing so will boost his own public image. He's already got a slogan handy for this eventuality: "Drain the swamp." All he's got to do is identify congressional Republicans as part of that swamp, in other words, which he might conceivably do at some point.

Terrorism targets Trump directly

Now we get to the more pessimistic part of the list. Donald Trump sells his name, around the world. He gets a whole bunch of money when someone else builds a building and wants to call it "Trump Tower Timbuktu" or whatever. So even though Trump doesn't actually own any of these properties, a whole bunch of them exist throughout the world, with Trump's name on them. Terrorists might eventually notice this, and decide that a weakly-defended apartment building in the Middle East somewhere would make a dandy target for an attack. If a Trump-named building was attacked successfully, that would put America in a rather strange place.

Would Trump react by ordering the U.S. military to protect all Trump-named properties worldwide? Is that a valid use of American military might or not? This is the president we're talking about, after all. So is an attack on him an attack on the U.S.? Barring that sort of response, one or two successful attacks on a Trump-branded property might make all the rest of them seriously consider the value of the Trump name on their buildings. This could easily lead to a collapse of the Trump name as a powerful brand. Again: is that a valid American foreign policy interest or not? Trump would certainly feel such an attack quite personally, so it's anyone's guess how he would react.

Corruption and scandal (Part 1: Cabinet)

This is certainly within not only the realm of possibility, but probability. While some of Trump's picks for the cabinet and for other advisors have an actual record of public service and a clear understanding of the sacrifices that must be made for such service, many do not. With Trump himself setting an incredibly poor example when it comes to ethically separating himself from possible conflicts of interest, it'd be easy to picture one of his inexperienced cabinet secretaries getting caught in a corruption scandal. While it's impossible to predict what shape this scandal will take, it's entirely reasonable to suspect that there may even be multiple scandals in the Trump administration. Of course, the outcome has already been listed above: Trump tweets out "You're fired!" and boots the corrupt advisor immediately, followed by claiming Trump knew nothing about the whole thing.

Corruption and scandal (Part 2: White House)

This is also a very real possibility. The scandal could hit a lot closer to home, and directly involve one of his family members or other close White House advisors. This would probably be some species of "pay to play" where money flowed to Trump (or the Trump organization) in order to get some sort of quid pro quo. Trump is leaving himself wide open to this sort of corruption, by refusing to put his assets in a truly blind trust. This would be a lot harder for Trump to attempt to brush off by just firing someone, obviously. If one of his sons is caught accepting something in exchange for a change in American foreign policy (just for instance), it might even cause congressional Republicans to turn on Trump in a big way. "He's gone too far," they'll sadly say, which brings us directly to our next possibility.

Impeachment and removal

At some point, Trump might just go too far for congressional Republicans. Now, this could happen due to scandal (see above), but it could also happen in other ways. Trump orders U.S. troops to do something wildly unpopular (or even illegal), for instance, like pre-emptively nuke North Korea. Or, perhaps, Trump makes good on his promise to "send them all home" and begins rounding up millions of undocumented immigrants. Or the president announces we're pulling out of NATO, in a fit of pique. There are indeed many ways this could happen (something that is not normally true of an incoming president, with respect to his own political party).

If Trump makes a spectacularly bad decision and then digs in his heels against any and all criticism -- up to and including sparking a constitutional crisis with either of the other branches of the government -- then Republicans in Congress could decide to get rid of him. It's really an open question as to whether Democrats would go along with this (which is also something not exactly normal). Would the prospect of President Pence give them pause? Republicans could successfully impeach Trump (in the House), as they indeed did with Bill Clinton. But to actually remove him would require the support of a large number of Senate Democrats, who might prefer a flawed (and powerless) President Trump to a very ideological President Pence.

Cabinet constitutional coup

This one is normally just a historical footnote not even worth mentioning, but I personally consider Donald Trump to be a prime candidate for a constitutional coup. Little known to most people, there is actually an outline for how an official (and fully constitutional) coup could take place in America. It's a holdover from the Cold War (and the aftermath of the assassination of J.F.K.), but it is still part and parcel of the Constitution every officeholder is sworn to uphold.

Amendment XXV, Section 4 states:

Whenever the Vice President and a majority of either the principal officers of the executive departments or of such other body as Congress may by law provide, transmit to the President pro tempore of the Senate and the Speaker of the House of Representatives their written declaration that the President is unable to discharge the powers and duties of his office, the Vice President shall immediately assume the powers and duties of the office as Acting President.

Got that? If more than half of the cabinet ("the principal officers of the executive departments") signs a letter stating that the president is unfit to serve -- for whatever reason they decide is valid -- then Mike Pence assumes the power of the presidency.

However, Trump could fight back if they suddenly decided he was crazy as a loon and a danger to America. This section continues, laying out what would happen if there's a disagreement:

Thereafter, when the President transmits to the President pro tempore of the Senate and the Speaker of the House of Representatives his written declaration that no inability exists, he shall resume the powers and duties of his office unless the Vice President and a majority of either the principal officers of the executive department or of such other body as Congress may by law provide, transmit within four days to the President pro tempore of the Senate and the Speaker of the House of Representatives their written declaration that the President is unable to discharge the powers and duties of his office. Thereupon Congress shall decide the issue, assembling within forty-eight hours for that purpose if not in session. If the Congress, within twenty-one days after receipt of the latter written declaration, or, if Congress is not in session, within twenty-one days after Congress is required to assemble, determines by two-thirds vote of both Houses that the President is unable to discharge the powers and duties of his office, the Vice President shall continue to discharge the same as Acting President; otherwise, the President shall resume the powers and duties of his office.

If there's a showdown between Pence (backed by over half the cabinet) and Trump, then Congress gets to decide. There would be a flurry of letters sent to Congress (from the cabinet, from Trump, and then from the cabinet again), and then Congress would have three weeks to vote. The bar for this to happen is actually higher than for impeachment itself, it's worth noting. The House can impeach a sitting president with only a majority vote, although the Senate needs a two-thirds majority to actually remove him from office. If the 25th Amendment were invoked, then both houses would have to clear the two-thirds bar.

This means there would only be two possible advantages to taking this route (rather than the normal impeachment process). The first would be one of time. Bill Clinton's impeachment dragged on for months (it started in the lame-duck session in 1998 after the election, and wasn't resolved until mid-February in the Senate). If Congress wanted Trump out on an expedited schedule, though, that three-week deadline might look awfully tempting. The second reason this might happen, though, is that Congress wouldn't have to decide or prove that Trump was guilty of any "high crime or misdemeanor," but rather than he was just unfit to serve -- again, for whatever reason they chose. It would be up to each member of Congress to decide whether Trump was too dangerously unstable to lead, or not. That's it. That's a totally different proposition than actual grounds for impeachment, which is why it's the second reason this route might be taken.

World War III

And finally, just for completeness' sake, Trump could get in so far over his head that the nukes start flying. There is pretty much nothing stopping Trump from ordering a first strike anywhere on Earth, although whether the military would follow such an order if it were hastily (or irrationally) given is an open question. What happens if the Putin-Trump bromance goes south in a big way? What happens if Trump demands China get out of the South China Sea and sends a few carrier groups to back this decree up? What happens if Trump starts bombing North Korea and it turns out they can hit an American city with an I.C.B.M.? It's frightening to even consider, but that is the ultimate power of the presidency we are about to hand to Donald Trump, so it at least deserves a mention.

As I said at the beginning, it's impossible to tell the probability of any of these scenarios playing out, although some certainly seem more likely than others. Let's all hope for the sake of mankind that this last one is just pessimism run rampant, though.

-- Chris Weigant

Follow Chris on Twitter: @ChrisWeigant