Jordy Nelson has 18 career TDs of 40+ yards, but 7 of them - close to 40% - came just last year. So while he is a tremendous big play, highlight reel threat, odds are that those numbers would have come down this year as last year was more of an exception, not the rule. The chances are that this GB offense would need to find different methods of scoring than last year so that aspect of it isn't as big a concern for me.
Bigger concern is down in, down out - the professionalism, the route running savvy, the 4th down conversions, catching the ball anywhere up and down a 9 foot ladder, the sideline awareness. No one else on the roster has all that and really no one else in the league could come in and do the same thing. Aaron will just have to find a way to spread the ball to everyone and anyone, like Favre had to do for most of his career.