Miles and Chizik are clearly the most likely because of one reason, Saban. They are at the two schools with the most Saban-envy (LSU and Auburn), which means their fans will be most likely to get antsy over anything. I'll be willing to bet that one out of Miles and Chizik will be gone by kickoff of the 2011 season (meaning one will get canned after one of the next two seasons). I'm betting on Miles. Yes, he won a title in 2007, but the locals still give a lot of credit for his title to Saban. With Alabama doing well with Saban, they will get restless if Miles pulls another 7 win season.
Petrino, Nutt, and Mullen are all new on the job, and they aren't at Auburn, which means they have security for a few years. Also, I don't see any of those three having the opportunity or willingness to jump jobs in the next two years. And even if Nutt is doing a weak job of recruiting like you say, he's still got a solid core for the next couple years, which will keep him pretty secure in his job until at least after Chizik or Miles is gone.
Obviously the only way Saban is gone is if Notre Dame buys him, and that's unlikely.