And he's still young. Goff's contract isn't bad for a starting QB, but I don't think you can fit two starting QB salaries under the cap. Lions can afford to pay a QB because so much of their talent is still under their rookie contract, but once the bill comes due on those guys, doubt it.
So there's the question, do you feel good about letting a lot of these guys go, once you can't afford them, because you've paid your QB? Or do you stick with Goff while these guys are cheap, and then get a young QB in line, for cheap, once you have to pay these guys?
That's the tough question. You look at the Super Bowl champs. Rodgers only has 1, and IIRC he was still on his rookie deal, so they could pay for that elite defense with Matthews, Woodson and Collins. Russell Wilson, same thing, cheap QB, so you could pay the Legion of Boom. Peyton Manning, the 2nd greatest QB of my life, needed an elite defense, on a lot of rookie deals, to win his second.
The two exceptions are the GOAT and Roethlisberger. Brady won his first 3 on a rookie deal with an elite defense, same with Roethlisberger. Then the Patriots were able to continuously remake the roster in different ways to make it work. The Steelers kept hitting over and over and over on skill position players in the draft (look up their RB/WR drafting, during Ben's time, it's insane), then they'd let them go without paying them. That's the greatest QB of all time, and a top 5-7 QB, and they both needed some good roster movement around them to make it work, because even the best QBs still just suck up so much cap space