It would if MS allowed things to devolve enough... but we can safely say that's not going to happen... so thus there's no reason to act like MS wont invest enough. If shader compilation worsens and doesn't get better... MS WILL be forced to deal with it.Linux, even with Valve efforts, will never dethrone Windows.
Like I said.. there's no 1 single solution to the problem, but MS for their part would make the API better in the ways it has to, while adding functionality, and also providing framework to allow developers to more easily tackle this issue. Things that a good platform holder should rightfully do.