IMO, Obama will not return for another run. If he can't beat and old man and a rookie teenybopper, he can't win ever.
Hilary won't be back either. She'll be 65 years old, and age will catch up with her. She pissed off too many party elders dragging Obama thru the mud for 2 months unnecessarily.
I think it'll be Evan Buyh - a Clinton protege who is everything Obama is, with a skin color more palatable to older voters who decided in 1958 that they didn't want Obama.
His running mate? A military man - Wes Clark, or more likely, Jim Webb.