The problem is, without the backwards compatibility and a high-performance core design, the customer base is really, really small - and that's the reason (in addition to Qualcomm having had an exclusivity agreement with MS, but only putting out crap designs) why every attempt of pushing a non-x86 Windows machine so far just completely and utterly failed.

The lower/ultra-low end market is a different thing - just look at the absurdly massive popularity of Raspberry Pi and their clones - but as said these are toys, not capable of being an actually usable general (as in: general population) computing device.