I do worry that Facebook will figure they might as well double dip on sales and advertising; future headsets are probably going to have eye tracking (ostensibly for foveated rendering and better avatars), and combining in-world advertising with exact data on how long people looked at them is a pretty compelling sell for what is fundamentally an advertising company.

They spent like 15 minutes of the presentation talking about how ethical they're going to be (re: AR glasses) and how trust has to be earned, but their ethics track record isn't exactly stellar.