I think (and hope) it'll be fairly fragmented communities, spread across lots of apps and websites and forums for various niches. Some communities will be built Discourse, others on new apps and sites built on ActivityPub, others will be built on completely new tech and ideas.

I really hope the large one-size-fits-all / winner-takes-all "social media" communities go away. It's their massive scale that creates problems like lack of moderation, toxicity. I'm really hoping we can capture the "forum feeling" of meeting and learning from cool/fun/interesting internet strangers.