Yes, because he's Favre and he's allowed to go on his own terms, just like every great quarterback has done so [Marino, Elway, Montana, Moon..].
He also is the reason why the Packers went as far as they did. Sure he didn't have a good game in the NFC Title game, but he's had a great season overall, for his age.
I still think he's got 2 good years ahead of him. The Packers will try to solidify the running back position, perhaps target a tight end as well in free agency, and they should be on their way back to the title game.
He won't retire.