FOSS NT Kernel... It would only be successful when it is really FOSS and not company backed single main contributor FOSS like Chrome or .NET Core. As a kernel contributor I want to shape my kernel, not being overruled by a decision done in a meeting somewhere on a campus I never visited.

You would need extensive partnership agreements like what Google has with Microsoft regards Chrome or Samsung has with Microsoft regards .NET Core. Challenging for smaller vendors.

Linux has a more pure (not owned) FOSS style making it successful.