I can't see Hamilton goon to the reds unless Alonso leaves. Perez has been tipped to replace Massa if he doesn't buck his ideas up, and if Massa is able to drag things along a bit and Perez gets bored waiting the I can see DiResta getting a job there.
Biggest question is who will go to Mercedes if Schumey doesn't renew his contract. They'd like Vettel but I can't see him gang anywhere fast. Perhaps Webber would look at Brawn the Kingmaker as his one chance of a stab at a title before he gets too old. Hamilton maybe, but Merc won't tolerate a whinging primadonna, so while it's on the cards I think they'd take Webber over Hamilton.
Who knows? TBH, the politics and back room dealing are a major part of the attraction.