[inphovore]

I suppose one must quibble with what one terms “blockchain.” The ledger part is fine, the distributed/decentralized part is inefficient.

Use hierarchical private keys (which can be delegated among sub-groups) and use a secure infrastructure of delegation (no strangers, only key holders.) with “trusted” delegation, delegate heads could still use redundancy for maintaining trust (triple redundant recurrent results.)

Ledger of a block chain, without the waste or 51%+ attack vulnerability.

A private blockchain.