I expect MS Windows to support Linux more and more over the years and I'll not be surprised if they'll make moves towards using Linux as the main kernal of Windows some day or even entirely switch to a Linux kernal eventually (only running win32 and and other WinAPI for legacy support). I'm convinced that it would be a viable goal. Their main problems with this decision (other than engineering problems of actually making the switch) would be that other Linux distros might get even better hardware support if hardware manufacuters would create drivers for Linux first and that it might become easier to develop and improve software like Wine, that enables to run old Windows applications on Linux. As for new Windows applications, those would be developed for a fork of Linux anyway.