If you are going to make a breaking change to the nostr protocol like this you might as well focus on key rotation because normal people don't use cold storage and even cold storage can get hacked.
Discussion
Certificates/delegates imply key rotation, because you rotate the certificate/delegate. For reasons of security and repudiation. Only the master is permanent.
As to what "people do" they'll have to do what we tell them is the right thing to do.