#crazyidea : a Mastodon instance, where every new account is a random generated fantasy RPG character, and you'd be locked out of editing your name, pic and bio; all of which would comprise your charactersheet. Followers and followees would be replaced by XP and level counters. Bots would administer loot/magic items/weapons and other both would pop up to be random encounters or dungeon crawls or even story lines run by admin GMs.
I've just been told about the Briar Project, which seems pretty awesome. If their approach could be extended with... ● multi-device / multi-node identities ● webserver based nodes for bridging to the classical web - mostly aimed at all those who don't need absolute security
Given those two (admittedly huge) extensions to Briar's model, and some Mastodon-level (or better) UX, I think this could replace facebook nicely.