[harpastum]

4k per eye would definitely be good enough. Text still wouldn't be crisp and clean, but it would be very readable.

VR headsets don't distribute pixels evenly across the entire view-space, the lenses concentrate the pixels toward the middle of your vision. So if for example you had a display that took up the center 25% of your vision in VR, it might have 50% of the actual display pixels. 50% of 4k is 1080p.

So you'd end up with a display that looks pretty large, but is only 1080p. Not optimal, but definitely usable.