I'm not sure what specific technologies "blockchain databases" is limited to -- but one use case that has been bandying around me head ... I think there could

I'm not sure what specific technologies "blockchain databases" is limited to -- but one use case that has been bandying around me head ... I think there could be a very powerful set of regulatory technologies created on top of blockchain style databases when used in conjunction with legally binding agreements intended to limit access to reads of the data. Imagine a data lake for "enforcing" audit-ability of reads -- 1. you may "store" some data in the lake -- say for example P2 2. if you "store" data in the lake you agree that you will not store that data anywhere else "store" above would in actual implementation be something like storing a key for decrypting the data -- which could be stored wherever in an encrypted form and the agreement would mean "i'm not storing the key anywhere and i'm not storing the decrypting contents in any form other than as encrypted by the key". You would leverage blockchain to ensure that all reads of the data are observable. Obviously you can't "enforce" that the data being protected is not stored in other places or in other forms -- however the agreement "i will not store anywhere else" can be given legal or regulatory force to provide a way to punish violators. The goal tho is to build a platform for explicitly acknowledging and communicating to both external auditors and the developers that "i'm not supposed to store this in other places". That's a technology problem which a lot of good faith implementors need help with solving ...