Windows on ARM situartion has not looked pretty. Windows CE is old. Windows phones look to be on free fall out of matkets.
Windows 10 IoT on Raspberry Pi is one plan for getting some life support for Windows on ARM.
Microsoft has not forgotten ARM. Soon Windows 10 will run on ARM processors and even run x86 apps! Will this finally make ARM as sensible CPU for portable Windows gadgets? Hard to say, but it seems that Microsoft is at least trying.