What VR could, should, and almost certainly will be within two years [pdf] 13 years ago
The state of the art in virtual audio is keeping pace with these developments. I've had some experience with research headphones that combine HRTF models with head tracking, and the result is uncanny - Except that the environment your ears are presented with has to match the strong priors from your eyeballs. So it will be awesome to experience virtual audio and video at the same time.