VR/AR is more unlike-in-capability than phones. If the hardware becomes a pair of glasses that have no friction in putting on, then it can engulf capabilities of TV, phone, PC, anything that has a screen. And unlike part would be to project stuff on real world, be completely in a virtual world, etc.

I just think that making the hardware is the toughest challenge. Zuck might be underestimating hardware progress.

If he is right, godspeed, future would be amazing. If not, we'll have net positive experiment out of this and it will accelerate AR/VR hardware dev.