Price is determined by what someone is willing to pay but value isn't. If the value from art comes from expression, then LLMs directly attack the core value of art.
Something tells me that doesn't alter the value of the art as expression of the intention of the artist, and not the assistant be it human or machine. In the spot painting case he was deliberately playing with this idea to the degree it added to the perceived value.
But someone has the vision and make it real. That which is real is a medium from one soul (or many) to you.
I still have to see someone using LLM to share a soulful vision of his.