RSS is fine, and it's not going away. Adding nostr pubkey links to RSS as a podcasting 2.0 extension is the way to go. @arkinox has done some work on this which you can read here:

GitHub

nostr verified podcast nip by arkin0x · Pull Request #1465 · nostr-protocol/nips

Nostr Implementation Possibilities. Contribute to nostr-protocol/nips development by creating an account on GitHub.