It seems to me that the goal should be not to require the other user to be using Emacs, since the underlying data is text files anyway. The open protocol approach seems most exciting, enabling people to use whatever editor they like best with the same documents simultaneously.

We’re out there, in clusters. The agency I most recently contracted through was probably a quarter Emacs users, and entirely the heavy-collaboration/always-pairing sort of developer.

Ouch! But true.

Fortunately, most Emacs users are likely hermits anyway.

so true... in 15 years using emacs I never came across another emacs-user in real life.

But even if I would find one and we wanted to use emacs together - How is that supposed to work? My config and how I use it is quite personal.

Also I don't understand what it could provide. Screen-sharing can be done with Teamviewer etc.