what if we just start with kind:1521 with opentimestampped events; this seems like such a trivial get and doesn't open the door of crypto/HD bikeshedding.
Regardless, if we do HD keys we'd still need to do kind:1521 stuff as described in https://github.com/nostr-protocol/nips/blob/key-invalidation-and-migration/37.md
what do you think jb55 (npub1xts…kk5s) ?