With Intel's acquisition of SiFive... for Windows to support RISC V they'd need to do that anyway. They did it for ARM64 (partially) and are struggling. They have to do bunch of stuff via emulation instead.
Changing to a completely different kernel would be something else.
I would like it, we need more open hardware. But I have no illusion that vendors like Microsoft, Google or Apple will first try to find a way to lock their systems down.