I'd love to work on a AR/VR "social network" (for lack of a better term). Facebook's SocialVR experiments are probably the closest to an actual attempt at doing something like this. I think AltspaceVR, Linden, and other smaller players building Metaverse style virtual worlds are somewhat misguided because they focus on fantasy over reality, which I think has a niche but doesn't appeal to a more mainstream audience.

One of the most exciting VR apps is Google Earth VR, which highlights that the "killer app" for VR will have telepresence at its core.