My opinion:

I don't think we should limit the future of Nostr to just the social network side.

Social Network is just one of the use cases of Nostr. With me, Nostr is an open protocol for building apps. What makes an app built on Nostr unique is that the app doesn't need to rely on a local database, and the developer doesn't need to handle account management. The killer feature is that users only need one account, then they can use all the apps in the ecosystem without creating other accounts.

Developers can build a chat app, a note-taking app, a marketplace, or just use NIP-78 for Redis replacement (key-value storage).

To be honest, if I treat Nostr is for social network only, there don't have any bright future. 

Besides Lume, I'm also building a game store similar to Steam or Itch.io and a few other small apps on Nostr. I hope this will gain more attention from developers and other normal users to Nostr.