I assumed this was possible - it was when I was working with very early VR prototypes.
I think what is going to end up being big is the setup where you have a camera on top of a monitor or TV that just does head tracking. As TV's get larger and cheaper (and projectors better and better) having no headset but nice head tracking is a great middleground to VR. Plus other people can easily watch you play (and it is easier for noobs to get into). Most games do not really need full 360 degree head movement - you can just turn around with a keyboard or controller as you normally would.
I think what is going to end up being big is the setup where you have a camera on top of a monitor or TV that just does head tracking. As TV's get larger and cheaper (and projectors better and better) having no headset but nice head tracking is a great middleground to VR. Plus other people can easily watch you play (and it is easier for noobs to get into). Most games do not really need full 360 degree head movement - you can just turn around with a keyboard or controller as you normally would.