Alex Smith, Bradford, Bridgewater, or Keenum are not likely to cause a QB needy team high in the draft to pass on a QB that they think is a legit starter. Smith's issue is age, Bradford has never stuck on a team, Bridgewater is a significant injury question mark, and Keenum is possibly a one hit wonder.
I can see a team like the Jags go after Smith as the final piece. There are other teams that need QBs later in the first:
Bills, Skins (if Cousins leaves), Vikings (if all three leave), Cardinals.
Bills - Cousins
Jags - Smith
Vikings - Keenum
Saints - Brees
Cardinals - Bradford
Washington - Bridgewater
Cleveland - Darnold
Giants - Rosen
Broncos - Allen
Jets take a QB or trade down a bit, then take a QB - Mayfield
If one of the QBs slip, I can see the Cardinals taking one, even if they get a vet in FA.
I agree that teams aren't going to pass on a franchise quarterback in the draft if one falls on their lap, but realistically is this a class full of potential franchise quarterbacks or are they more likely to be good rather than top tier?
Josh Allen's comparison has varied from the next Cam Newton to Blake Bortles.
Josh Rosen apparently has some concerned with his attitude.
Baker Mayfield has people concerned with off field issues.
Some have suggested Lamar Jackson change positions to make it in the NFL.
Sam Darnold seems to be the main guy that doesn't have as much concern aimed his way compared to the others but he's by no means perfect.
We've seen worse classes without a doubt, but I could see a team like the Broncos with a play off calibre defense deciding to go for a veteran like Sam Bradford whose main problem has been staying healthy, but when he is he's very capable. So instead of risking another rookie quarterback they could try to win now and use their pick on the best non-QB. Likewise the Jets might see someone like Bridgewater who was an ascending young quarterback before his injury as more appealing than someone in this year's class, and give them a greater chance to push on for the play offs because they were better than expected. The Browns are, well, the Browns.
Don't get me wrong this year's class should see a number of quarterbacks taken, but if the Browns, Broncos and Jets land their ideal player in free agency like Cousins, Smith, and possibly the likes of Bradford or Bridgewater, then that changes the draft. At that point the Giants are likely the team to draft someone in the top ten, and if that's the case I suspect the Cardinals, Bills and Redskins will be clamouring to trade up above us!
This year could be really exciting to watch how things unfold in free agency and the first round.