inkan on Nostr: Yes, but an attacker will also be able to decrypt messages encrypted to the old key. ...

Yes, but an attacker will also be able to decrypt messages encrypted to the old key. Also, the old 10044 is validly signed forever, so an attacker can actively seed these announcements in any place that hasn't received the update. Inkan fixes that as a by-product of its key rotation system, which records revocations on-chain. I may try to add DMs, right now I'm exploring if a double ratchet is feasible.