I'm beating the drum for pet-names, too but I also must confess it's not trivial to bake into a UI. I think what could work is:

* Default petname to users chosen username at the time of following them. So when Alice and Bob follow you, their lists of follows would add "Karnage" to your pubkey

* Alice could edit it to "Karnage the design guy" in her follows list

* Now if you change your name to Fiatjaf, you would still be "@Alice@Karnage the design guy" or @Bob@Karnage (or the reverse: "@Karnage the design guy@Alice" @Karnage@Bob

* Bob would always see you as "Karnage" but maybe optionally as "Karnage (Fiatjaf♻️ )", allowing Bob to update his petname with a click on ♻️ . Or the symbol could open a popup that would allow Bob to dismiss the display of the alternative name

* Clients should avoid petname collisions. Troll Fiatjaf aka Karnage should force the user who already follows Fiatjaf aka CEO of the nostr to pick another petname.

* If Dave follows two petname Fiatjaf's, clients should detect that and not resolve @Fiatjaf@Dave but show both of them to pick from