I can't have a message or a LinkedIn connection without other person registering with messaging app or LinkedIn, willingly. When they setup LinkedIn or message me, they are fully aware of the fact that I will either access or receive that information. Not comparable.

>> face recognition, memory of interactions etc should stay on device

It can't be processed there, chip too small. And physics don't allow us to make chips smaller anymore.

I wonder, though, if it could be hosted on a phone and processed here. Not realistic for current smartphones, but if we talking about theoretical, it's would be a neat trick.

I can imagine a future device that has three parts: lightweight glasses with HUD as a thin client, a glovelike input device to track your hand, and a small box you put in your pocket/bag.