Brady’s legacy is pretty much set, not that it ever was in question. But he never had to actually win a championship in Tampa; he has removed the irrational image in people’s minds of him having a nervous breakdown at midfield after failing to “dink and dunk” because defenses are no longer outsmarted by the 7D chess moves coming from the sidelines.
An NFC Championship Game appearance at age 43 (and 40 TD passes) is icing on the cake. An easy reference that pretty much stonewalls any argument that he was dependent on Belichick. Anyone who still argues Brady still isn’t worthy of #1 on their insecure QB rankings list, or insists on ThE mOsT AcCoMpLiSHeD bUt NoT tHe GReATeSt was never going to change their opinion, so a Super Bowl with Tampa would be awesome but doesn‘t win over anyone. It would be awesome, though, just because it takes the idea of him being the greatest ever by a huge margin and increases it to a gigantic margin. But it’s more of a giant middle finger to all of the “but but but Belichick and the system” idiots, which would be the best part.
Belichick doesn’t need to win a championship without Brady, either, but he needs to build a team that can win and compete. If he winds up with like total 12 seasons without Brady, a couple of playoff wins, and an overall sub-.500 record, I don’t really know what to say. He’ll be a guy who maximized the Patriots dynasty and was very much responsible for the success, but beyond that, you can’t pretend he did things that he didn’t do, despite all of the theoretical greatness that gets mixed up with facts. Hopefully he’ll make build a contender or a team where he can demonstrate his vision and coaching prowess independent of Brady.