This is good analysis in my opinion.
However, I think the biggest thing folks have overlooked is the most valuable asset facebook owns:
The largest database of human faces on Earth mappable to real people.
Put a tiny video camera on a Rift, shrink the size to a pair of ski goggles and all of a sudden
these apps start to make real sense. Look at a person, it facially recognizes them and pulls up all their "like" stats. One might even augment reality to such a point that entire environments could be overlaid with agreed upon conditions.
Q: How many people does it take to create a reality?
A: One. But two is better.
(P.K. Dick)
Zuckerberg is not an idiot.