After listening to the Citadel dispatch with hzrd and Stewart, it got my brain spinning. 
Maybe you can build a "gated community" on top of nostr, with all different kinds of plugins based on NIPs

And then at any point, community members can fork the entire stack to create a new community. 
Could be useful for communities that require moderation, but the underlying data ends up being totally forkable. 

Members could pay dues for hosting costs of the CDN / relay / DB. You could even customize the login experience to something more traditional (like user just creates a password which will be used to generate an ncrypt) and the community can store that. https://image.nostr.build/42368ccf30d6ec24138d173bf74c6b7b61ead390718bdb9a28fcc3b407f7934c.jpg