The only reason to use Windows is Win32 desktop software and these PC lite systems offer no path to the desktop other than a mixed bag emulation.

MS has not stated here is the future of the Win32 desktop across Arm/x86 systems with native software to extract the full performance of the hardware. They could have leveraged a unified executable for Arm/x86 as a way to separate the Win10 desktop from legacy Windows, get popular Windows software all on-board with emulation the backup not the primary system.

Windows Arm only supports native UWP apps which are dead in the water. Anything interesting on Windows bubbles up from the desktop and these systems will always be sub-par in that area.

If look around MS watcher sites and PC fan sites there is intense skepticism and outright hostility towards these new PC lite platforms.

I do not think they will even carve out a niche, especially with x86 systems featuring 5G support in the pipeline.