After this draft class of QB's - there will likely be another 4 potential starters that are on their first deal - approx 1/2 the league. On top of that, your high priced star QB's are all approaching the end - Big Ben, Brees, Brady, Rivers - 4 out of the top 10.
If analytics start creeping more into the NFL, draft a young QB - keep your cap hit reasonable for 4-5 years. Spend to make those around them better and not 20% of cap for the QB. This eventually should effect the top figures getting so crazy as there would be less teams wanting to pay top money for a mid tier QB.
This of course all depends on the success of these young QB's - but if I were a GM, that's how I would approach it right now.
Tag and trade Dak to someone looking to still pay QB huge money (even if you just get a 1st and a 2nd)
Draft Mac Jones
You'll have him surrounded by hopefully a healthy and improved Oline, good RB, and top WR group.
Stock up in draft on defense and spend the saved cap money on defense as well.
Basically you'd have to decide which is better for the team
Dak on long term deal
or
Extra draft picks
2 FA starters on D
Cap flexibility in future.
Risky QB bet - with vet back up (Dalton, Smith, McCoy)
Running a quick mock draft without the potential draft stock on a Dak trade (Trade down to 18 with Dolphins for 18 and 36)
1. Mac Jones - QB
2. Trevon Moehrig - S
2. Greg Newsome - CB
3. Jabril Cox - LB
3. Tyler Shelvin - DT
4. Adrian Early - OT
4. Paulson Adebo - CB
5. Jamin Davis - LB
6. Nick Eubanks - TE
6. Rakeem Boyd - RB
7. Jose Borregales - K
Probably looking to draft another LB or CB with the other potential 1st rounder (Nick Bolten, Zaven Collins or Jaycee Horn were all available after 20th pick)