[Originally mostly posted as a comment over at Balloon Juice, expanded here when I decided I liked it enough to make it a diary.]
So! Lots of things to predict. Republican race, the general, the economy, foreign affairs, years to come, and so on. And all in the comfortable knowledge that these predictions are highly unlikely to actually affect what does happen! Please feel free to offer agreements, disagreements, counter-predictions, and the like in the comments.
And heeeeere we go...
THE REPUBLICAN PRIMARY:
Romney can't get any traction among culturally-Southern and Appalachian areas; the South goes for Gingrich and Appalachia and the midwest lean Santorum. Romney wins unimpressively in Mormon country and blue states, but comes up slightly short of enough delegates on his own, but Republican superdelegates put him over the top. Gingrich refuses to endorse Romney, but Santorum does in exchange for the VP slot and a pretense of a party unity ticket. Paul refuses to endorse him and instead supports Gary Johnson on the Libertarian ticket.
THE ECONOMY:
Oil companies jack up prices in a deliberate attempt to influence the public mood, right up until in a surprise move Obama orders a full-scale public RICO investigation of the major oil companies, at which point prices mysteriously decline and sweating oil executives say "See? It was oil speculators, not us." Romney sides with the executives.
Europe manages to avoid a second recession, but remains largely moribund. Rumbles of discontent about the Euro continue, mostly in Germany and France, but not enough to break the system. Greece stays in a state of moderate unrest, but somehow nobody in a position of power ever gets around to pointing out that Greece's experience really does show how that following Keynesian economic projections would be a really good idea, going for stimulus rather than dramatic government cutbacks in the face of recessions.
The US continues recovering from its recession. Increasingly-worried Republicans in the House scramble to find some way to pretend they've done anything about jobs, but can't restrain their worst impulses to load up their own legislation with poison pills that ensure every vote is party-line and doomed in the Senate, or else subject to enough revision that they then can't accept a conference report that removes the poison pills.
FOREIGN AFFAIRS:
Iran continues to threaten and bluster, but does not take action, aware that their actual military position is not strong and that 'defeating Iran' would make an excellent election-year issue in the US. Iran holds off on making any nuclear tests or announcing any nuclear weapons on similar grounds. Romney is smart enough to hold off on calling for an immediate invasion, but is forced to take a generally hard line through the primaries regardless.
Israel continues to prepare for a military strike on Iran, but holds off on uncertainty that the US would automatically be drawn in under the prevailing circumstances, particularly the worry that it could be a purely air war without either side able to actually invade the other.
The Afghan situation remains mostly stable; Karzai's government isn't strong enough to rule the country on its own, but nobody else there is any better, and it's not SO unpopular as to provoke mass rebellion. The US continues trying to find a way to inch away. Romney demands that we 'win' Afghanistan without putting forward any remotely workable plan for doing so.
Fidel Castro finally dies (or is acknowledged to have died), letting Obama cheerfully add one more notch to his Dictator Bucket List. Raul Castro is still alive and no serious effort at rapprochement is made. Romney glumly writes off Florida.
THE GENERAL ELECTION:
Obama's win is never in serious doubt, as he holds leads of at least 5% in states commanding over 270 electoral votes all the way through, including PA, OH, CO, VA, and NC. Dissatisfied conservatives convinced that the race is lost stay home in droves to protest, exacerbated by Romney's frantic lurch toward the center immediately after getting the official nomination. Romney is unable to come close to matching Obama's campaign resources, as his high-dollar donors are tapped out and the small-dollar donors don't trust him. Obama beats his 2008 margin, adding Arizona and Georgia to the ranks of blue.
Conservatives wait a whole two weeks before claiming that the race clearly shows pervasive systematic fraud, but their hearts aren't in it (at least for most of them) given the margins involved and wins in some completely Republican-controlled states.
THE HOUSE AND SENATE:
It's not so lopsided further down the ticket. Warren easily beats Brown in Massachusetts, and Berkley takes out Heller. Kaine wins Virginia (boosted by a solid Obama win there) and Keitkamp beats Berg in South Dakota. Tommy Thompson loses the Wisconsin primary and so Tammy Baldwin holds Wisconsin. McCaskill loses a slowly-reddening Missouri, however, as does Obama, and Nebraska is long gone, while Arizona turns out to be disappointingly far from competitive in the Senate race. Net is zero in the Senate, swapping Nebraska and Massachusetts back to their more ideologically compatible parties and Nevada and Missouri trading places.
The filibuster continues to be an infuriating problem, as Democrats look to the unfavorable 2014 calendar and worry about the possibility of losing the chamber (though they'd have strong odds of retaking it in 2016). Democrats do reclaim the House, recapturing almost all of the New York seats they lost, both New Hampshire seats, several in Pennsylvania, and a bunch across the midwest that were 2010 flukes (untenable Republican holds even with gerrymandering). A few Southern seats come back, but not many, mostly in competitive urban or suburban areas rather than ancestral-Democrat seats. The margin is narrow, though, under ten, leading to the infuriating ongoing relevance of the Blue Dogs. It doesn't matter anyhow because the filibuster in the Senate prevents any useful work from getting done.
STATE HOUSES:
Thanks to the courts redrawing the New York state legislative maps, Republicans finally lose their grip on the New York Senate, leaving the state finally in complete Democratic control. The Republican redistricting of New Hampshire turns out to be a dummymander, as their efforts leave them with only 5 'solid Republican' districts and no 'strong Republican' districts; all the rest of 'lean Republican' at best and result in Democrats reclaiming the New Hampshire state government with a vengeance (including holding the governorship).
Texas sees a Democratic resurgence, thanks to Romney driving down turnout and, for the first time in many years, not having a Texan either on the top of the ballot or having one leaving the White House. It's not enough to retake the Texas Senate, and falls just short in the Texas House, but thanks to the gerrymandering Democrats do get more votes cast for them in aggregate, showing the direction the state will be going in the future.
States across the northeast and midwest take advantage of their opportunity to throw out the crazed teabaggers who came into town and proceeded to attempt kamikaze governance, doing their best to destroy institutions so they would take a long time to restore them. At least two states come under total Democratic control and immediately perform mid-decade redistrictings.
THE AFTERMATH:
Republicans determine that Romney's problem was Insufficient Conservatism, and that a contested election is not in the best interests of the party, so they rapidly settle on Santorum as their nominee, letting him immediately begin running for the next four years on the grounds of being Next In Line. Thanks to the unfavorable 2014 calendar and the narrow Democratic hold on the House, Santorum takes credit for Republicans taking a microscopic 51-49 edge in the Senate and a House majority of under 10 seats (which is nonetheless more active than the Democratic majority thanks to higher party unity). Republicans immediately and arrogantly abolish the filibuster, and Obama's veto pen gets hundreds of uses in his last two years, with confirmations few and far between.
Mark Begich loses narrowly in 2014, not due to unpopularity but due to a not-completely-incompetent-or-scandal-ridden Republican opponent in a deeply Republican state. Mary Landrieu loses by a fairly wide margin with an unenthused and shrunken Democratic base in Louisiana behind her. Mark Pryor faces a stiff race, as does Kay Hagan, and one of the two doesn't make it. Republicans throw an enormous amount of resources at Al Franken in the belief that other people hate him as much as they do, but he holds on comfortably. One race comes out of nowhere and tanks, either due to a terrible flub, unexpected retirement, a surprisingly good Republican opponent, or just a bad turnout in some state.
Santorum runs in 2016 and is decisively trounced, Goldwater-esque, as the playing field no longer is winnable with any combination of red and purple states; over 270 electoral votes are into territory of 'leans D' or higher and any Republican nominee will have to be able to win over blue states. Democrats reclaim the now-filibusterless Senate and retake the House. Insurance companies are bailing on health coverage, moving more and more Americans into the state and federal pools, but most red states have refused to implement their own (trying to defeat the increasingly-popular Obamacare) so there's basically the blue state pools and the federal pool; the federal pool is more expensive because the healthier populations of blue states aren't in it. Medicare For All is finally enacted in recognition of the fact that it's the de-facto situation anyhow. By the 2020 elections, Republicans are indignantly proclaiming themselves the 'true champions of Americare' and claiming that it denies their contributions to continue calling it 'Obamacare.'
Old White Male Republicans are rapidly aging out of the electorate. Latino voters are solidly in the Democratic camp (not as strongly as the black vote, but better than two to one after decades of Republican Latino-bashing). Texas is in Democratic hands by 2020, leading to a massive haul of congressional seats switching into Democratic hands. The House is solidly in Democratic hands for years to come. The Senate is closer, but with the demise of the filibuster 'close' is no longer anywhere near as much of a problem. Scalia, Alito, Roberts, and Thomas hang on to stubbornly wait for an ideologically-compatible president to come along, but ultimately their time is past.
So! There you go. My predictions. Mostly predicated on a disgrunted Republican base, changing demographics, and a dash of personal analysis.