Sure, I think for augmenting relays a dht be cool or for discovering relays/nostriches in the first place or as a place for relays to crawl and check if a peer is available to be read from.

Otherwise, I'm not sure it'd provide a twitter-like experience with online/offline/roaming/behind-nat peers.

Nostr works pretty well today because it emulates the way most applications work - notes are concentrated and duplicated to a few places and clients read from them. It's a lot like ActivityPub but with keypair ids. Moving beyond that model will require some pretty radical and practical insight that no one has managed to produce and scale yet.