Well, at least this is a big step in the right direction. This kind of technology should have become mainstream already, or at least high end available and used as the 8800 is nowadays (much more attention towards it, and much more money being made and to be made, resulting in much more research and development).
There is no need for this piece to be a single piece. And I don't mean the head phones or similar. I mean, a sensor to get the coordinates and direction of the head, that can be placed in a static fine-tuned location, and no need to give up on the mouse just yet. Just as software corrects and displays different images for each eye, and ear to shoulder rotation, it can (easily IMO) make corrections and allow the head of the player to look a bit closer or away.
p.s. The "no need to give up on the mouse just yet" is in my opinion a way to do other stuff with it. A simple example: You don't need to shoot at whatever you look at. Plus the mouse is still a very sensitive piece of input device that will enhance the gaming experience, head mounted display with virtual reality or not... unless naturally you provide gloves with positioning sensors and their representation in the virtual world.
And then we'd have glove gestures, combined with voice commands, and WoW will have spell casting experience worth of "magic simulator" (like flight simulators)
I believe all of this tech is available nowadays, and it just needs to be "put to good use", something that can be done with minimal effort. I still can't believe big corporations haven't seen the profit opportunities ahead in this road.