Video with z-depth, maybe computed from stereoscopic video. The complexity added would then be similar to an alpha channel. This would break video out of the rectangles we see in all UI design.
Wikipedia articles follow a format which makes it easy to find information. Perhaps site maps for a VR web could be arranged according to a convention so that users can easily figure out where to look for specific information. Early VR we web tried to do this by arranging content like rooms in a building, and streets, but that is cumbersome to use in practice. I think the wiki format suggests a much better approach can be created.
Volumetric video, spatial website navigation design guidelines, and augmented reality are high on m wish-list.