So I’m talking about playing previously Windows-only games on Linux, e.g. via proton.
I don’t know about the libraries etc that are used - is it possible for Microsoft to use some legal voodoo, for example, to suddenly end it all, and make the use of their libraries illegal (if they belong to Microsoft in the first place)?
Or could there be other ways of interference?
That’s true, but white room reverse engineering requires two people to do what one person could do by just stealing the code. Plus, the person reading the source code would be “burned”, they can’t work on normal implementation after browsing the source.