I was more asking why you think Nostr possibly succeeding in the future means that we don't need other technologies. These two technologies, analogically are basically RSS : Firebase :: Nostr :: DWeb Nodes, so it's not like you can build every type of app on RSS, you eventually need datastores. Why do you view this as some battle where there can only be one winner? Did cars make planes unnecessary for you?

did:key has secp256k1 variants, and if you used did:dht, you can just put your npub in your key set, along with any other keys you want to add of any types. Additionally, you can add relay endpoints to your DID's service endpoint routing section.

Why would a federated RSS feed be 'the beginning of the end' for decentralized app datastore tech (think: decentralized version of Firebase)? Those two things are wildly different, so I'm not understanding your comment - it's like saying 'the automobile was the beginning of the end for the airplane'.