I believe the killer app is going to be journalism, and not really VR but simply 360 video streamed from political and social hotspots around the globe. Political uprising in country X? Celebrity overdose/break-up/marriage? Observe in real time as if you are there via captured 360 video. For the technologists interested in virtual world virtual reality, it will be a let down. But for the majority of the public, 360 video will be VR. It will get more interesting for us technologists when multiple 360 video streams captured in the same space can be merged in a Photosynth like fashion to create a true virtual space one can navigate independent of any individual 360 video stream. That will be very much "true RV" and of actual places and actual events. Journalism is, IMHO, the VR killer app.