Gunfighter, I think the foreign policy differences between Obama and hard-line foreign policy wing of the Republican Party are almost entirely superficial. I imagine that some influential people would prefer Romney, but in this (like most other things) there is scarcely any daylight between the candidates. I'm sure some on Wall Street would prefer Romney, too, but that doesn't stop them from giving millions to Obama. If the current guy is fine for their purposes, there's no reason to change.
And Joe Biden is a delight. He would be a disaster of a president, mediocre at best. But I think Obama and Bush before him were disasters, so I don't know. Maybe Biden would be like Chester A. Arthur, expected to be terrible and turned out pretty okay.
As to the ostensible topic of this thread, it will be someone who, like Palin, is more ambitious than intelligent, willing to take part in a likely losing cause for the sake of career. Santorum was too much of a dick during the primaries. My guess is somebody in Congress, Portman or Paul Ryan.