Reusing phones as VR displays, as in this project and in Google Cardboard, is nice from a cost perspective. But from a quality perspective I think it's a step wrong direction. VR that's a little bit wrong or inferior is not almost as good; it's VR that some people can't use because it'll make them sick. This might match the current generation (if the latency is good enough), but the current generation isn't quite good enough, and the next iterations of VR are heading in directions that phone-in-a-box setups can't realistically follow.