If Favre wants to return, then I welcome him back. I would wonder if he really means it, but the Packers are better with him. It could also lead to QB Aaron Rodgers likely departure in free agency after 2009, but risks in free agency are always part of football anyway.
What is the worst case scenario if Favre returns to the NFL? Peter King spells it out:
Overwhelmingly the team that makes the most sense to sign Favre for a couple of years is Minnesota. The Vikings are training Tarvaris Jackson to be their quarterback of the future, but he's an unproven commodity with promise at best. Their offensive coordinator is Darrell Bevell, who was Favre's quarterback coach for three years, from 2003-05. They have a close relationship. Not Steve Mariucci-Favre close, but Favre has a lot of respect for him. Imagine Favre in purple. It's an absolutely vomitous scenario for the Packers, imagining Favre playing for their arch-rivals -- and imagining Favre charging out of the tunnel at Lambeau Field for the opening game of the 2008 season. Lambeau Field, Monday Night Football, the night Favre was supposed to have his number retired for the Packers.