[tlrobinson]

Multisig might.

"To complete the Coinbase Vault offering, we will be adding multi-signature (“multi-Sig”) technology in the coming weeks to enable customers to manage their own vault security."

It's not clear exactly how that will work, but if it's, say, 2-of-3 and Coinbase only holds one of the keys then it would.

[ukd1]

Multisig would be good, especially if it's actually a address keypair, as it would allow you to verify the balance held exists.