if microsoft changed their apis wouldnt new games just not work on proton?

Also, this is antithetical to the purpose of Windows when it comes to backwards compatibility. Remember that one of its main selling points is the ability to run old programs, regardless of what version it originally targeted.

Believe it or not, the industry would probably start a riot if ms breaks that paradigm. It's like, one of the main reasons that it has the market-share that it does.