It's not possible to build rosters like what you saw with the 70s Steelers/80s 49ers/90s Cowboys over the long run anymore. With how free agency and the salary cap is structured the best you can hope for is a dominant 3ish year window where you have all the pieces in place before some players inevitably get picked off.
The Patriots are a fluke with arguably the GOAT HC and QB, they've sustained success despite having average parts elsewhere for years because of how mediocre the competition is around the league. Their skill position talent and defense fluctuates but Belichick/Brady have maintained their greatness over the years.
The Steelers have had a relatively long run of success but over the last 8 years they've been to one conference championship and are on the verge of missing the playoffs for a 3rd time over that span, nearly every other season.
They had a 6 year run that included 2 SB wins and another SB appearance but those teams were not dominant up and down the roster. They were actually pretty similar to what we have now, except better. Elite defense, ball control offense with a game manager QB who you hope makes a few plays a game. They were not elite up and down the roster like the 80s 49ers or 90s Cowboys.
Those types of teams aren't coming back, at least not for more than a 2-3 or so year window when everything falls into place with elite players on rookie/cheap deals before their salary inflates. With the NFL how it is now you have to pick and choose your spots and strategically spend money in the right places while going cheap at others.
