Ask HN: How can we get close to Full Dive VR?

I just saw a post about EEG sensors that someone is shilling https://news.ycombinator.com/item?id=43994490 thats mods should probably remove or ban as the top comment there posted it out its some dude trying to get you to buy things from their store, but on a Sunday morning here it made me think just how far are we away from full dive VR, a recent example is the black mirror shows final season episode for example. Anyone here read VR light novels and such we know that supercomputers and AI are a super part of this.