I mean that if you can produce a fingerprint image corresponding to a blockchain hash and it matches your fingerprint 20 years later, and this is linked to 20 years worth of blockchain recorded credential information, I would find that very compelling evidence that you are who you say you are.
This idea of having 20 years of linked entries in an append-only distributed log is very powerful, and is the basis for the "idchains" system discussed here:
I mean that if you can produce a fingerprint image corresponding to a blockchain hash and it matches your fingerprint 20 years later, and this is linked to 20 years worth of blockchain recorded credential information, I would find that very compelling evidence that you are who you say you are.