I'd also love to see sub keys that can somehow be neutered or destroyed. I imagine signing an event using something like a 2/3 multisig or whatever that essentially destroys the other keys for signing and replaces it with one only the holder of the master key(s) can see. A password reset like behavior. Of course, someone who gets the master key(s) would still become king. No way to fix that without offline protections like we have for Bitcoin.