I have to say that I'm not really sure. I never expected Bill Clinton or G.W. Bush to get re-elected but they both did.
Personal opinion aside, just going from a "Mr. Spock" perspective I would have to say that, short of a major October surprise or some other measurable, unforgivable scandal, Obama's pretty much got it locked in. That being said, let us all remember that the political pendulum is always in constant motion, as we seen the last round of elections, even after the Obama landslide, many republicans were elected the next cycle.
The question is how far it swings before the it swings back. If the elections were held today, Obama would be a shoe-in as the republicans aren't really doing that well in moderate, centrist America. Further, they really have no definitive platform or common agenda. Their candidates appear weak and not quite ready for prime time. And then there are those goof-balls semi-candidates sucking all of the air out of the room, distracting the more gullible right siders, with their snake-oil, carnival barker shows. I would venture to say those folks make up about 12-20% of the GOP voting block and they are so stoned on tea everyone is shying away from their sillyness as to not be made guilty by association. But they still need tthose folks, none-the-less. How can they suck up and yet remain seperated from them all at the same time? That's gonna be a tough one.
No, I'm gonna have to say, get ready for 4 more years of Obama if things don't radically change.