Don't know that there is a one, ironclad, definition of a franchise quarterback. I can certainly see that by some definitions and views, Dak is one
But to me Dak is not, for several reasons, among which are:
1. Too many missed easy, sure (assuming the receiver catches the ball) touchdown or game winning/saving throws. Every quarterback misses some, Dak's just got too many.
2. Not enough of an on the field leader. By that I mean I've never seen him even glare at a receiver who misses an easy catch, or a blocker that doesn't give enough effort/gets penalties nor does he exhort the players to be better, yes he high-fives them after a good drive or play, but if the team is out of sync he doesn't put the fire and energy he has to the team overall.
Don't misunderstand me, I do think he's an above average quarterback, top 10 for sure, but the "franchise quarterback" realm for me is rarefied air, the Staubach/Montana/Brady group.
Dak's not there yet, imho. He may get there, but after this long I think we'd see it. Doesn't mean he can't win SBs with this team ever, and you obviously don't need the franchise quarterback to do so (Dilfer, et al). I'm talking about Dak based on the "franchise quarterback" discussion alone, not his ability to win SBs...