There are other prohibitive problems with this idea. What happens if someone dies or the private key is otherwise lost? What if the private key is stolen and

There are other prohibitive problems with this idea. What happens if someone dies or the private key is otherwise lost? What if the private key is stolen and the thief uses it to authorize a dirt-cheap sale to themselves? What happens if the item is sold but the "token" is accidentally (or deliberately) sent to the wrong recipient? What happens if the courts determine that someone else is legally entitled to the work in question (e.g. via divorce judgement) but the current owner destroys the private key out of spite? Additionally, this system does not solve any practical problems. If I am a collector of stolen art, I don't really care about some ephemeral blockchain token, all I really care about is being in possession of rare art that I can personally admire. Finally, it is impossible to generate a reproducible hash based on a physical object, so there is nothing preventing someone from keeping the original and selling off a fake in its place, forever corrupting the supposed chain of trust established by the artist.