When I think of a future with Open Social Media, I imagine three pillars.
1) Microblogging (ActivityPub), for sharing thoughts with strangers, ephemeral community building, and broad+global reach.
2) Forum / Stable Community (no good solution yet, AFAIK), for discussing, planning, buying/selling locally. All within a distinct group of people, membership of which can be managed.
3) Peer2Peer (Scuttlebutt?), for talking directly to friends, family, nearby people, and easily sharing files.