[Obi_Juan_Kenobi]

The 'corporate blockchain' described above would probably be a federated one. Participants would use private keys to sign and validate transactions, with full knowledge about who else is in the network. It's a simple quorum mechanism, or some elaboration thereof.

It is not 'trustless', but it is decentralized. You're basically relying on a majority of participants to behave ethically and not collude. In a situation where collusion is impractical or has little reward, this can function fine.

An example of this is Blockstream's 'Liquid' crypto which is validated by crypto exchanges. The security model of this coin isn't great compared to Bitcoin, but it arguably has advantages over the simple custodian model.