I need help implementing it. It exists at https://github.com/nbd-wtf/nostr-tools/blob/nip41/nip41.ts but I need someone else to implement it elsewhere so we can compare things and clarify the spec. Then we can start using it.
Forwarding is complicated, #[4] proposal I think explains it best.
Root key with delegation and fiatjaf's proposal look good. However, to use them still requires transferring to a new key.
Using out-of-bound means, like NIP-05, to be the source of information about the new key, combined with a means to revoke a key looks like it could be an option.
Discussion
The beauty of NIP-41 is that it doesn't need any existing client to support it. You just need one thin micro app that people visit every now and then to update their contact lists after invalidation events and then that gets pulled in by other clients.
#[0]