While a good portion of developers will still be switching engines and staying there, as an AR developer, there isn't really anywhere else for me to go aside from developing with WebXR. Because of this, I am glad to see these changes.
Apple's Vision Pro support as well as Niantic's Lightship ARDK are currently only available via Unity. In general, many of the tools for new AR platforms and devices are developed for Unity first. With all of this backlash that might change in the future, but for the time being the overwhelming majority of AR support goes into Unity.