I don't know. I think most Brett fans can and will separate his exploits on the field from his exploits off the field (such as they are) and will always see him as one of the greatest quarterbacks in the game. Five ... ten years from now, no one will be talking about Brett's text messages. They'll be talking about his passing record or his number of consecutive starts. The texting stuff is a blip that will be forgotten as soon as the next scandal comes along.
I mean, come on. Michael Vick is starting and playing some pretty smokin' football. How many times have you heard a commentator remind us that Michael Vick is a convicted felon who did jail time for dog fighting? The fans have all but forgotten Vick's past, and his problems were eons bigger than Brett's.
History will remember Brett Favre for his skill on the football field, not for his stupidity off of it.