As we can see in https://forum.snapcraft.io/t/snapcraft-register-key-failing/7732, store developers can very easily lose their private keys, even before they could sign anything with them. For those cases, a destructive form of key revocation (when all signatures are invalidated) would probably work. A more selective form of key revocation (when signatures prior to the action are considered valid) requires more elaborate support for timeproofs. In the interim, `snapcraft` CLI could be more informative about how to backup and restore keys (from `~/.snaps/gnupg`) and key-name conflicts.