Not sure, but I think I've read that the proposed $175 million dollar cap is actually already based on spreading the loss over a few years. Greg Tompsett from Cover 1 just had a tweet about this a few days ago. Buffalo Rumblings also had something similar below.
Buffalo Rumblings Cap Article
I don't expect the cap to be any higher than $175 in 2021, as such the Bills will have to do a lot of cap gymnastics on contracts for Jerry Hughes, John Brown, Micah Hyde, Vernon Butler, and Quinton Jefferson to have any hopes of re-signing Milano or Daryl Williams. Best case is they add a second year to those players Hughes, Brown, and Hyde move a lot of the money to roster bonus, and spread the impact of the contracts over two years rather than one.
Good news is our GM is cap smart so I know they'll find a way to get under the cap. Just dont expect large roster turnover,