Is it too early to pick the 2012 election results? Let me preface my prediction with a warning: I'm a guy who has NEVER voted for the eventual nominee in the primaries. So my analysis is worth about what you're paying for it.
That said, the GOP nominee in 2012 will be.... drum roll... MITT ROMNEY! Not necessarily because he's best, but because he's next. Democrats fall in love, Republicans fall in line. Go back as far as the eye can see... you would have to be eligible for social security to have voted for a GOP candidate who wasn't the obvious "next in line" (Goldwater, 1964). After that, it's former VP Nixon, his VP Ford, Reagan (runner-up to Ford), his VP Bush, long-time bridesmaid and Ford's running mate Dole, Bush's son Bush 43, and McCain, who was runner-up to Bush in 2000. By this logic, nobody but Romney has a chance!
Additionally, my guess at this point is that Palin doesn't run, but the chance that she might breaks up the "anybody but Romney" vote a little. I also think that unless we see miraculous economic recovery, Romney's rep as the savior of the 2002 winter Olympics and his experience as a real businessperson will look very attractive. And at the end of the day, I think more folks will embrace demonstrated academic prowess (albeit not Ivy League--he was valedictorian of BYU) over folksiness (even facile folksiness) of the sort you might see in Huckabee.
Of course, Obama will run again. The question is, can he win? That hinges on two variables. The first is whether he will pivot like Clinton toward the center. I don't see that happening, but I could be wrong. The other is whether he catches the big break of economic recovery. It doesn't even need to be his fault, but if things turn around and he can take credit for it, well, he wins. I think you can count on a very positive media environment for him; he won't have to swim upstream against NYT stories on "jobless recovery" or anything like that. But if his best answer is only "it could be even worse," well, ask Carter, Hoover, or even Van Buren how that worked out. And that's the zillion-dollar question.
I'll bet he at least makes it close. I'm just too bullish on the American people and economy to believe that we'll continue to languish in this kind of trough for two more years. We'll see!