I disagree with you here.
No way is Hillary going to want to jump in now.
Firstly, too many of her supporters HATE Obama and they'd have to also vote for him, in order to vote for her.
Secondly, if Hillary were VP and they pulled off a win in November, the Dem's would be in such bad shape by 2012, that Hillary would never, ever get a chance to run for President again (she'd be too old by the time the Dem's have another shot, given what a four-year, Obama-lead Presidency would do to this country).
Thirdly (and lastly), Obama would look like a huge pu**y if he changed his running mate right now. The only people who would not switch to McCain/Palin would be the one's who would never switch in the first place. And there's no way he's going to get 50% (or close) that way.
Fourthly, Hillary will not take the VP candidacy because it eliminates her main weapon(and defense), “victimhood”! She would no longer be able to use it were she to run against a woman. It is one of the reasons she has not attacked Palin while stumping for zer0bama.
“Thirdly (and lastly), Obama would look like a huge pu**y if he changed his running mate right now.”
He looks like a huge pu**y right now. No need for waiting on that!
But even given that you're right, Obama has so few original ideas of his own that I can easily see him saying to himself, "That game-changing thing of McCain's was cool. I want some of that. Let's see... who to pick? Who to pick?"
We'll never regret being prepared for the worst. Agreed?