In the end it should be easy to realize. All you need to do is programming a controllable camera (controlled via headtracking of the VR Glasses) and as mentioned the second angle / camera which is easy in a 3D world.
I would wonder if the big graphic card and or graphic engine companies would not already have an easy to implement brick just to add 3D Support.
But as visible Zwift does not seem to base on one of the big graphic engines. If it would we would see graphical enchancements every few years / months like Raytracing.
Maybe it‘s time for Zwift to concider that. Not just because of VR…just to get a fresh look.
Personally I can‘t imagine wearing a VR Glass whilst sweating eventhough I really love VR Experiences generally.