In looking at the 2008 election, there really was a perfect storm: financial meltdown, Bush was unpopular, the Iraq war was unpopular, Obama was new and sounded good (if you didn't listen to much of the substance), McCain wasn't the strongest GOP candidate.
With all of that, Obama only got 53 percent of the vote, McCain 46 percent. McCain won 22 states.
Given that the luster is gone, Obama has performed so poorly, and the economic conditions really haven't improved, I think it's more likely than not that he loses to whomever wins the GOP nomination.