Just because "remote social presence / coworking" is the future, doesn't mean that Facebook is on track to capitalize on it.

For example, I'd much prefer a "mirror-sized realtime video" (i.e. a "window into the other office") kind of experience, where I don't actually need to wear a helmet.

And there aren't even that many technological obstacles to that; just good TVs, with good software, and fast enough internet connection. Add a bit of eye/head tracking (to approximate 3D from different viewpoints) and it'll be very real-like.