This is a serious question.
Throw out the conspiracy theories about Obama somehow overturning the 22nd Amendment and running again himself.
Biden is a national embarrassment, and even the Democrats know it, so the only way they're going to run him at the top of the ticket is if they're actively suicidal.
So, does Hillary go again? Does Michael Nanny-State Bloomberg jump party lines (again -- he was a Democrat up till 2001) and run? Who else is on the Democrat bench that could throw their hat into the ring?