I see it this way:
McCain gets the nod and takes Romney as his VP to fill in that economics gap that McCain's admitted to and attempt to appease the conservatives.
, I'm calling it B. Hussein Obama. Hillary's suffering from the problem she walked into the race with: everybody's already formed an opinion (good or bad) about her and there's no room to grow. B. Hussein has been (and will continue) to gain ground as undecideds go his way (there are no Hillary undecideds). Hillary won't deign to be second fiddle, so no Veep slot for her. She will, however, flame out as she loses to B. Hussein because she is incapable of losing gracefully or being magnanimous when she does. I don't know who he'd go with as a Veep - Edwards already has the stink of death on him.
Ron Paul is the wild card - if he runs as an independent he'll put B. Hussein in the White House.