A warning and a perspective from an insider who has been through this before.
doesn’t have to be blockchain based, but there should be some sort of incentive for people to take up the burden of hosting (and moderating, I guess) like blockchains have for people to run nodes, or instances will start shutting down eventually when the people who were footing the bill get tired of it. Or maybe I’m wrong and instances will survive on donations and goodwill of their moderators. I’m not sure how that’d work if communities get really big though