Dynasty's, HOF QBs and HOF HC's make the NFL a lot of money. Without them, we've have a league full of modern day Dallas Cowboys organizations.
The league, sales and media need those things in order to truly feed the machine.
As long as BB, Brady and the Patriots exist and are relevant, everyone profits.
A TV analyst once said (before KG, Pierce and Allen formed the C's Big 3), the NBA is a much better league when the Lakers, Celtics, Knicks and Bulls are Championship contenders.
That was one reason Mahomes was the "answer" to the growing problem, "who takes over the league when Brady and Rodgers retire?". Forturnately for the league, Brady broke the age barrier and has continued to pay dividends.
It's also what makes Josh Allen famous and Deshaun Watson newsworthy. The NFL is always needing more QBs to become pop culture stars. The mantle has to be passed. Otherwise, the NFL is boring without great QBs.
Also the reason why the "Rodgers' Saga" was a good and bad moment for the NFL this offseason. The exposure was great (NFL news) but the reality was sobering; "The Green Bay Packers without Rodgers?!?" Nope, that is a story that has to end well.
New England and BB are still the media darlings until they are no longer newsworthy.