On the NFL vs NBA/MLB front, the NFL is been on the “hard” cap side. You can pay anyone whatever you want, but there is a ceiling. In baseball or basketball you can go over that ceiling for an individual, but you pay extra (luxury tax) or there are specific omissions from the cap (Bird rules/max deals). The NFL system is preferable, to me, I terms of overall competitive balance, but it definitely is about at is breaking point, at least in the way in which we have all come to understand it. Part of that is an exploding cap that makes valuation difficult even over the length of a basic (4-5 years) deal for a veteran player; part of it is the shorter average career and larger roster size which means that players who do make it past their rookie contract have larger expectations of the deals they will accept.
You can cap the individual player hard and allow some exceptions to try to ensure competitive balance and consistency for fans (NBA), or you can cap the team hard and let the teams and FA market determine what a player is worth (NFL). I don’t think there’s a world where trying to do both of those things is good for anyone. QB pay is clearly spiking right now, but whether that is a problem is TBD. Foles just won the Super Bowl. Brady, Manning, Manning, Rapist, and Brees won 6 in the past 10 years and were top paid guys. Rodgers, Wilson, and Flacco all won while they were guys who were clearly good but not yet paid as elite. Teams could swing towards cheaper, basic QBs like many have with RBs. Given the rules that favor QBs and passing that seems unwise, but the “next” BB will be looking for market inefficiencies at various positions that they can manipulate to get an edge over many seasons.
Brady and B.B. made each other, but they also found each other at the perfect time. The next guy might have a genius way to spend $30m on 5 or 6 guys at skill positions who can be led by a fairly mediocre QB will a certain skill set the same way Brady has made otherwise pedestrian looking skill guys who are not premier money players into world beaters.