That's difficult to determine because what other players might we have with his contract out of the way? Would Stephen and Jerry take that money and invest it in players of need or would they splurge on one flashy player? Likely it's the second, but who knows? Who would we have in Dak's place? Who would they have gotten to replace him? The fact is, he's been struggling in Quarters 1-3 for a couple of games for whatever reason. Would another QB have the same issues? We don't know.
I think he'll get better through the regular season, but we don't know for sure if we'd be much worse with a different QB. McCarthy would call a different game with a different QB.