Luck is 27 and while still fairly young, it's not like he is still a really young, developing QB, and I think we've seen much of his upside. The following guys all appear to have a lot of productive years remaining, and I think enough to meet the criteria where you could start a franchise with them and not feel shorted based on their age:
Aaron Rodgers (33)
Matt Ryan (31)
Joe Flacco (31)
Andy Dalton (29)
Russell Wilson (28)
Kirk Cousins (28)
Matt Stafford (28)
Cam Newton (27)
Derek Carr (25)
Marcus Mariota (23)
Dak Prescott (23)
Jameis Winston (22)
I'm not saying Luck isn't in the top 5, so your statement isn't far-fetched, just that (a) it doesn't dismiss the overall craziness of Pagano's opinion, and (b) there are a lot of players that are still fairly young and doing well in a franchise QB role, while Luck has definitely not separated from the pack in any way, coaching and supporting cast aside, just watching his decision-making and overall play, he is far from where we thought he'd be at this point in his career.