This will actually start to become more common - OpenXR is starting to be implemented in earnest and makes the games hardware agnostic.
You’ll still get store exclusives, but the point is that games will be able to run using the openXR runtimes on steamvr headsets, wmr headsets, oculus headsets without any specific work from the developers. If companies decide to artificially limit games to their headsets (cough, oculus, cough) then they can continue to do so, but you should see games that “just work” across all major VR platforms.