No question about it. Franchise QB's are exceptionally rare. When you have one, you pay whatever it takes to keep him. It's not debatable.
But you may have to go cheap elsewhere. When Seattle paid Russell Wilson and their top defenders, they went cheap on the o-line. And it almost got him killed.
Similar decisions may have to be made in 3 years.
The key is that they need to keep drafting well. You can let good players go if you can replace them with good players on rookie contracts. You even gain high compensatory picks when you lose good players.