1) "Connectivity, so getting everyone in the world on the Internet."
2) "The next one is AI. I think that that's just going to unlock so much potential in so many different domains."
3) "[The next computing platform] - I think that's going to be virtual reality and augmented reality."
For all the flack that Zuck is getting in this thread he lays out a pretty concise vision of what he needs to do to continue the FB's juggernaut run.