Eh, I don’t think that holds up.

I might buy the 4th person as “someone outside your continuum or reality,” but I’ve yet to see a language construct specifically for that. Fictional characters invariably use second or third person to refer to the audience outside their world.

Streamers talking with their chat audience aren’t fictional or otherworldly though. I don’t see a linguistic difference between a streamer asking the chat what game he should play next, to Bob Saget saying “Home viewers, if you have a funny home video, send the tape to the address on your screen for a chance at appearing on our show!” It’s a communique addressing a large scattered audience through audio/video telephony soliciting a reply. The only real difference is round-trip latency.

While I think the phenomenon of live streaming and their audiences is interesting and presents a fairly new experience, I don’t know if it’s “we’re inventing new pronoun tenses over here.”