This would be idea. The only issue is that to get the full power of eye tracking integrated into the rendering system you need a camera that does at least 1000f

This would be idea. The only issue is that to get the full power of eye tracking integrated into the rendering system you need a camera that does at least 1000fps and even that is too slow for some stuff (researchers who use saccades as a behavioral readout in monkey research often use an implanted eyecoil because cameras are too slow). Those cameras are not cheap but maybe with a little math they can get away with using a slower one that costs less. Ultimately I expect this to happen officially because it is just too powerful an interface and there is so much useful data to be gained (plus scientists would love oculus forever). Probably won't happen in the near future since as Plamer pointed out in one of his talks it turns out avatars only need to look in a probable direction to seem realistic.