Absolutely no way this has any chance of happening, but just for the sake of argument:
Bledsoe has far, far, far more fire in the belly at this point in his career. Whatever you think about Bledsoe you have to believe he is desperate for a ring. You don't have to watch every Packer game to notice the way Favre has just been giving up and conceding defeat for the last several years. He just chucks it up there, whatever, willy-nilly -- "oops, another interception, guess we lose again". No thanks.
I personally don't think Favre has ever been more than slightly better than Bledsoe anyway. He is far more mobile and that does matter, but not as much as some believe. We all know that scrambling QB's almost never win the SB. Accuracy - Bledsoe, strength - draw (but Bledsoe more accurate on long passes), decision-making - Bledsoe (lately, anyway), leadership - tough to say but I would guess the people on these message boards aren't the only ones who think Favre is acting like a jerk right now. And, Bledsoe knows the Parcells system inside out.
Silly, silly assertation, really.