It's already being done. SMI, Tobii, etc. already have working implementations. Nvidia have also shown off some cool stuff of theirs.
This is an early impression from a couple years ago: Source
Pimax already has the mount and port built into the headset, I'm not sure which company will be offering the accessory, or if it's their own implementation. Point is foveated rendering is already here, it's not some pie in the sky idea years away. Starbreeze already uses it for Imax (so I was told on another forum) too.