I’m thinking that Obama will become so unpopular that she will have to run against him. Again, think Ted Kennedy running against the unpopular Jimmy Carter.
I don’t think the Dems would cross their black base, and challenging Obama would never be acceptable to the vast majority of them. Carter was a white guy from the South, which is very different.
Yes, If Obama's Likability goes significantly below 50%, Hillary might come out of the Woodwork. If Healthcare fails to pass and his numbers plummet, be assured she and her minions in the press will come out in droves.