I would say there is a more likely than Windows becomes open source and (some) Linux distros will switch to use the windows kernel than the scenario you put for

I would say there is a more likely than Windows becomes open source and (some) Linux distros will switch to use the windows kernel than the scenario you put forward. The amount of work it would take to switch Windows to use a linux kernel is mindbuggeling. One thing is the actual task of switching the kernel but documentation, tools suppor, drivers, end user training etc etc makes this scenario unrealistic. It wouldn't even bring any benefits to Windows. It already has a perfectly fine kernel