Windows on ARM (WOA) is dead on arrival (DOA).
What made the success of Windows? Every time a new release came, it came with 100%, or almost 100%, compatibility with every application and driver that existed before. In fact, what every new version of Windows was additions, new capabilities, that developers could embrace, and as a matter of fact take as upgrade incentive for their own business matters.
The release of Windows Vista was the first to cause serious harm to this, and to all software developers out there. That was when Microsoft decided to change the device driver model. This in effect broke every existing device and left users forced to either wait for hardware vendors to ship a compatible driver (never came) or to purchase Windows Vista compatible devices.
That alone almost broke Microsoft. But the install base was so big, everyone took their time to consider Windows Vista, that in fact taking just 3 years before upgrading left enough time for a number of device drivers to come along. In fact, this set of device drivers of the Vista era were shipped as Windows 7 back in 2007.
Everyone then was happy to upgrade and return back to their business.
Then Windows took a big wrong turn with Windows RT, a release that effectively broke application compatibility. No one ever upgraded to Windows RT. Big fail. Fortunately Windows RT was not the only Windows release, Microsoft indeed also shipped Windows 8. That almost failed too, but application compatibility was kept and device drivers were not changed. In fact Windows 8 took a hit only because of the UI changes, Microsoft thought that that would be a useful addition despite the fact that desktops could not take advantage of most of what was new (touch UI).
Windows 10 is released since and you know that it is successful because, again, application compatibility and device driver compatibility. The only reluctance to upgrading is that the system comes with a surveillance tool (that phones home personal data every few minutes), and ad placements in several places. Not enough to convince the majority of Windows users to avoid it at all cost, even though it is known these days that Windows 10 is evil.
Windows 10 S was then released, in 2017 and broke application compatibility. Microsoft indeed chose to only let applications from their own garden be allowed to install, essentially killing vendors out there not willing to submit themselves to uncalled for slavery. We are in 2018 and it is still too soon to tell, but there is good reason to believe that Windows 10 S will fail just like Windows RT. Even though you could find a justification as a software vendor to develop and sell software through Microsoft garden store, it appears that it is a bit too strong a thing to accept for most sensible vendors out there, essentially because Microsoft is willing to act like god : has death and life power on to you, and you lose the ability to control software that your own customers effectively install and use. Your own customers cannot install software from your website anymore.
We learn that in fall 2018, Microsoft will ship Windows RT 2, their second attempt at derailing the x86 era of software, by introducing ARM emulation. Of course, that was a non secret, this comes with compatibility problems for applications, and also zero support for existing x86 device drivers. If you read what was said before, this is effectively twice the reasons enough for Windows RT 2 (also known as WOA 2) to fail in the market. Of course, to be successful, Microsoft would have to stick it to every mouth by essentially forcing OEMs to include it in PC hardware. Never going to happen, because that would incur major risks to all OEMs out there.