With a decisive loss in North Carolina and just a narrow win in Indiana, I don't see how Clinton can even make a straight-faced argument to the superdelegates that she should be the real winner in this nomination fight. She can make noises about West Virginia and Kentucky, but it's over. She might stay in because she's feisty and won't admit defeat, but color her dead. We're where we would have been if the Democrats hadn't had their rules making the competition for delegates proportional instead of winner-take-all. Remember that there was a point when everyone knew that McCain had won, but he still had to go through the motions of campaigning in some of the remaining states until he had clinched the necessary number of delegates. That's where Obama is. He might have to wait for the superdelegates chime in, but it's all over now. The focus in all the media stories from here on out for her will be "why did you lose and when will you get out?"
So now Obama will have to concentrate on winning back those voters who supported Clinton and told pollsters that they wouldn't vote for Obama in the general election.
As for Michigan and Florida, if I were the Obama team, I'd make a gracious concession to those states and let their votes count, even though it would give Hillary a bunch of popular votes and delegates. He's still going to win and he could heal some of the wounds in those states.