What if a susbsequent owner loses their private key in order to transfer that COA to a new owner? (This is true for anything on Rarible as well, obviously). Now they own the physical art, but cannot transfer the digital COA...
The Timestamps are great. Kind of reminds me of what factom did. Being able to upload a pdf into a hash.
Our COA does require the artist to generate and secure the private key of their creator address. We could technically custody it for them (as Verisart does) but we are a Bitcoin company and strongly believe in self-custody.
The owner providing the transaction ID alone may be a strong enough assurance for prospective buyers. They'll have record of it in both the wallet used to make the transaction and the purchase confirmation email. Signing a message with the owner address private key is the ultimate assurance which can be done with most modern wallets. So really, they just need to maintain access to the wallet.
But yes, in both cases maintaining the COA requires responsibility. Like Bitcoin