A centrist like Bayh might be able to pull it off...
Still, I think Bayh is a serious contender to replace Biden on the VP spot should things get worse.
I think Bayh missed his chance, but he should at least try in 2016 and get his voice out there. But he's not exciting at all and will be a boring bye bye.
I would like to see Obama shake things up on the ticket, if anything I think a female deserves to be VP, a competent female from the Senate. Its time, and its clear that Obama is going to lose a lot of white males, so his only shot is keeping as many Female voters as possible.