Well.. obviously winning in Seattle will be tough for anyone. So would beating SF, Carolina, NO, and even Philly. GB gets in though, with Rodgers on the field... they are capable of getting hot, and going to the SB. There are few true difference makers in sports, he is one of them.
No doubt winning in any of those places would be tough, but I do think Seattle is much more difficult. Well you almost definitely need a QB in the NFL, not sure how effective the Pats would be without Brady, Broncos without Peyton, Saints without Brees. I could go on here. I think we saw that with the Packers recent play, the difference between the first string and second string at the most important position. They went from nearly being a lock to win their division to fighting just to hang on.