[ChrisSD]

When I asked HN about the licensing for windows.h and similar header files, there was some incredulity that MS could ever give them a permissive license (or even a slightly less restrictive one). And this was just for the public header files that define a public interface!

So I think it unlikely because Windows developers aren't calling for it and Linux developers don't care about it. Sure they'll open source particularly services and applications, especially as they move to more platforms. But I doubt they'd open source Windows itself.