Or they are simply making Windows 10 compatible with ARM. Wouldn't be the first hardware agnostic OS.
That's not just what they are doing here. They wouldn't have bothered with making an emulator for Win32 desktop programs if they just wanted their OS to run on more hardware. There is more to it. Windows will be running on ARM devices, fully functional, UWP or Win32, thanks to a partnership with Qualcomm & an MS investment on a jaw-dropping emulator.