Would you care to explain what you mean by "the bandwidth just isn't there"? VR is more than just mobile devices; all currently available VR headsets can also do PC VR, whether via a wired DisplayPort link or a wired or wireless network connection.

As I see it, the only absolute upper limit for VR is the resolution and frame rate of the VR headset displays, as well as the quality of the optical stack. Rendering of the graphics can be done by anything from a single high-end GPU in a PC up to a beefy server in the cloud—although in that case, of course, network latency and video compression will impact the experience.