BC would make it a much easier to market but the motion tracking may not allow for it. Hopefully some of the better titles will be updated to support PSVR2 but I wonder if that would require they be upgraded to PS5 native apps.
I'm not sure what you could do to emulate the sensing of the headset (it's the lightbar and the camera that act as the sensor, I guess it really does not have any other sixaxis sensors inside the headset? that's crazy that a 1280×800 camera 8 feet away was considered good enough for VR motion detection,) that would be a clear problem unless there could be a way to have a "virtual head" converting the PS VR2 sensors into position and acceleration data for the game.
As far as then controllers though, doing "virtual hands" might be tricky because there's more finer movement to transcribe, but they could also just default to requiring old PS Move and PS Camera equipment for older games. (I don't think they'd go to the trouble of selling a lame "LED Pack" to stick lights on your PS VR2 helmet.) Newcomers to PS VR2 would be left out, but at least you wouldn't need to keep both headsets out if they could do a little bit of the work internally.
Hm. I don't think the controllers will be an issue, but the camera possibly. Hopefully a patch can fix that.
All games for PS4VR require the camera, unfortunately. That's how it works, as I understand it, that the camera watches the lights on your headset and controllers (sort of like Wiimote, albeit backwards from Wii, technically,) and translates that into gameplay movement. PSVR doesn't rely on motion sensors, it relies on visual tracking of markers, aka little LED bulbs on your head and in your hands being seen by the camera.
This Sony's PlayStation VR review shows you how to bring virtual reality to your living room. Get Playstation VR games and try it out yourself!
www.lifewire.com
...Seems like such an easy concept, just make the new thing that's replacing the previous thing work with both thing's games. But once you think about how PSVR worked, you realize that the situation is frustratingly complicated.