If you combined this with multifactor authentication (e.g. fallback to a password for a 100% trust score), it could potentially match your change in biometrics

If you combined this with multifactor authentication (e.g. fallback to a password for a 100% trust score), it could potentially match your change in biometrics against a diagnostics knowledge base and use any new data following to further train the diagnostics knowledge base. Of course, that would have to be opt-in with patient confidentiality as strongly defended as possible (there needs to be laws and regulations defending privacy with this model), but it would be an interesting source of data collection.