Fuck no! Brett is surely one of the all time greats, but having him come back for one more year after preparing the team to play behind Rodgers would be detrimental to the franchise. They could lose Rodgers, a possible franchise QB, for good and have to start all over.
If Brett wants to play again he should, just for a different team. The Packers need to take care of the Packers, not let this guy hold the team hostage because he has the itch to pay one more year.