I believe the scheme above allows for all these features to be built, and I can't think of anything else better, but there may as well be, who knows.

The only problem with finding out is that when you find out it's often too late to switch because of network effect (this is the fate of Nostr itself and probably all of its subprotocols). Any small network effect is already too much. This is not to say you shouldn't try and error, I'm just stating a conundrum.