Ability to delete private data from private data storage and private state database on demand by a client request, without having to wait for the typical blockToLive period prior to purging. The blockToLive mechanism is insufficient for use cases that need to be compliant with GDPR, where data must be deleted upon a subject's request.
API to purge a private data key from private state, private data store, and transient store on an individual peer (could be done before or after or instead of DelPrivateData() chaincode API).
This story would help if a single organization should no longer be authorized to a certain piece of private data. They could call an API on their own peers to purge the private data, while the other organizations could retain it.
The shared ledger only has a hash of the private data. Each individual peer maintains their own private data stores and ensures the private data matches the on-chain hashes. So deletion from a single org's peer(s) would not be a divergence issue with respect to the shared ledger.
If the private data should be purged from all organization's peers on the channel, that is covered by FAB-5097.