Possible "game changers" for Obama include plugging the oil leak, peace between the Palestinians and Israelis, and World War III, although these events would be almost entirely outside Obama's control.
Looking ahead to 2012, Republicans need a candidate who can shake up the electoral map, which currently consists of "red states" and "blue states," even though there's not much difference.
The GOP—a stupid acronym we use only so we don't have to keep repeating the word Republican—will have to decide between a moderate "establishment" pick and a more conservative Tea Party favorite. In reality, both candidates would embrace similar policies in the general election.
That candidate will then face off against Obama, whose charisma, compelling personal story, and professional political operation will prove formidable. Actually, Obama will probably win because he's the incumbent. And because voters always go with the guy who's taller.