An interesting and hopeful post by Hofstra political scientist David Michael Green here (h/t Counterpunch) on how the most significant achievements of a successful Obama presidency could potentially not be substantive policy change (though that would certainly be one element), but rather substantive changes in US's political culture to be intolerant of rampant military spending, empire, foreign adventurism, antipathy towards all things government and embracing of all things market, flippant standards for presidency like "who you might want to have a beer with" and admiring presidents who "decide from the guy", making big progress in healing the weeping wound that is US race relations, and more.
It seems wildly hopeful and vaguely unlikely to me, but I don't think Green is arguing it will all come true even if Obama's successful, but rather that one or more of these are possible, if not likely outcomes of a successful presidency. (I really only skimmed his article, but I think he's defining successful as essentially "popular" (well-liked) by the end of his term, re-elected, and effective enough to lead us in a direction of real recovery of jobs; he explicitly says that Obama's policies may end up being liberal or centrist, but that the real important long-term effects, the real hallmarks of the Obama age, could be changes in attitudes of the American electorate. I guess I posted this because I agree that these are possibilities, they would be incredibly important breakthroughs, and I see them as rather more likely than substantive progressive policy change from Obama, though if we get universal health care, I will definitely give it up for the big "O". Though if we get single-payer health care, I will give him mad props, big ups, and eat my hat. With some hot sauce perhaps. But I would eat it gladly.)