Favre is good, but at times he can be the worst.
He can still play another year, but he has some physical problems he's dealing with right now.
Last year he started off great, then finished the season like a bum. Thats a sign of him being old and tired. The game will pass him by if he stays too much longer.
He'd be a great back up quarterback but his legend and his ego will not allow him to come off the bench like Doug Flutie, Kurt Warner, Drew Bledsoe, Boomer Esiason, Kerry Collins and so forth..