i can see the use for blockchain is maybe to send sensitive information like maybe Dr records and lawyers papers.. i think this can be done if you maybe could attach a file to the transaction..
i could be wrong and just talking and if i am correct me ...
sensitive data such as doctors records not on a public blockchain, would have to be private and only accessible by medical establishments
also think about all the data bloat of 7 million people having the flu. or getting a tooth filled
blockchains work by being distributed. so this alone is duplicating the data into every doctors office and hospital..
and also weak because every doctor and dentist has the ability to add/change records
somehow i cant see it being feasible for medical records.
however situations that can be useful, because blockchains are about storing data long term and permanently in multiple locations of access
noting doctors specialities and access level, insurance
log education results of students
recording new laws and court cases
social security/public funding
passport
births and deaths
i can even envision one blockchain being the identifier for all of the above
which could then lead onto other uses like a sidechain where the data can be used in many creative ways