Microsoft isn't giving up on ARM for Windows. Much like the semi-custom Ryzen processors for the Surface Laptop 3 series, the new 13-inch Surface Pro X tablet will use a custom SQ1 processor developed by Qualcomm.
https://www.notebookcheck.net/Microsoft-Surface-Pro-X-now-shipping-for-999-with-brand-new-SQ1-CPU-and-Adreno-685-graphics.441297.0.html