My guess is, the only team he'll come back to is the Vikings. If Green Bay blocks that, he'll take his $20 million "services" contract, and be done with it.
if he does that, just in my personal opinion, thats a joke. considering how he's played into the "i only play for the love of the game!" coverage espn gives him, he takes the bribe because his ego would be hurt playing backup, then i don't want to hear how he's the one football player who does it all for the love of the game, and not the money, ever again.
If he really did belive that, he'd just stay retired rather than backup, not need to get payed.