It does seem like there's a trend where having a good to great QB isn't enough if you can't build enough of a roster around him due to $ or other factors - Deshaun Watson, Matt Ryan, Matthew Stafford come to mind. I wonder also how much more he could make in national marketing deals (like Rodgers, Mahomes, have done) if he makes the Bills a regular contender - obviously easier if the team isn't cash strapped.
Still, the market is probably set at around 40 mil a year for him, and I would guess that's what he'll get.