Health plays the biggest factor to QBs aging. Peyton couldn't do it because of his neck injury. Brees played to 41, Brady to 45, Favre to 41, that doesn't mean every QB can play into their 40s. But I think the idea that QBs have a finite window is wrong. Every QB ages differently. Some guys age much more gracefully than others. Rodgers won an MVP at 38 (Allen should have won though, threw for more yards, ran for more yards, had more total TDs, was sacked for less yards and less times, only advantage rodgers had was turnovers and it was a big one. But that shouldn't determine the MVP. Rodgers was the most efficient QB that year, but if Purdy couldn't win it being the most efficient in 2023 why should Rodgers have won in 2021)
I wouldn't count on Penix playing past 30 though.