I'd bet on Obama toughing it out. Romney and Perry will slaughter each other in the primaries, though I'm no sure who'll win. I'd probably bet on Perry (better hair), but he wouldn't fair well in a general election. For one thing, despite the fact that they hated each other, people will associate him with the last imbecilic Texan to hold the office. Plus he'll be too far to the right to gain moderate support. That prayer stunt the other day will help him with the crazoids who still worship Palin's silly ass, but that doesn't help you win nationwide elections. The GOP is in a situation where the candidate more likely to win the primaries by appealing to whackjobs can't win the office.
As for congress, who the hell knows. The conventional wisdom is that Obama's party will take a hit, but at the same time, the GOP is pretty seriously fucked up right now. The Tea Party fissure hasn't even started to get big yet, and will cause them a great deal of trouble for years to come. The Budget issue reflects more poorly on both the GOP and the TP than the democrats. S&P seemed pretty clear that it was their obstruction that caused the downgrade. Add to that their inexplicable hard-on to screw with Medicair, which is instant death for a politician. Last time around they were able to ride on an anti-Obamacare [alleged] mandate, but that's less and less the attractive strategy as people become more accepting of the fact that it's a done deal.
Honestly, I don't really see things looking too different in 2013.