The President will be facing voters for presumably the last time. This in the context of being the first person of "color" will add voters to his column who right now feel dissappointed or apathetic.
The economy should be back on the rise by the middle of next year. By the time 2012 comes around there should be a really positive record to tout. This rebound would have happened regardless of who was President, so this will be a lucky outcome.
Democrats will have a long list of accomplishments that be able to thrwart some of the anger coming at the President from various quarters. This will give reason enough to fair-minded independents to be for Obama.
Republicans will have a fierce primary that will force the eventual nominee too far to the right in terms of cutting government, and social issues. President Obama will be running to "protect" America from the Republicans, similar to Clinton in 1996.