Linux

Linux isn’t a replacement for Windows. It’s its own thing, with its own issues but also advantages.

Linux isn't a replacement because Linux isn't an operating system. The "battle" isn't between Linux and Windows, it's between Windows and specific distros, like Ubuntu or Fedora. Mainstream Linux will require one of those to up their game when it comes to hardware partnerships and customer/end user support. Doing so will require competing against Microsoft along those same business areas, not just from an engineering perspective.

Unfortunately, I don't think that will be easy. Microsoft is incompetent at a lot of things (incl business most of the time), but they have unlimited money and leverage, and their relationship with the US govt means they're unlikely to see any antitrust scrutiny when they do illegal shit to suppress competitors.