It feels like the community would need to be the authority for this. Perhaps some sort of distributed network like BitTorrent or *shudder* a Blockchain combined with something PGP-like. You could say “contact me at BF55AE33”, and the network could convert that to a pgp-signed list of current pointers that you maintain. This could include IP addresses, so a DNS lookup for BF55AE33.distributed-identity is possible. Current email address. Social media accounts. Even a short profile, harking back to the .plan days.