So an art training will become more like pro sports training where “success” means to be top 100 or so in the world. Note it does not prevent one to do arts (or sports) as a hobby. People didn’t stop playing chess after Kasparov lost to Deep Blue.

Given how quickly AI image generation, and creativity generally, has progressed, I think it's perfectly plausible that within ten years we will be able to tell an AI "create a work of art that is unique, highly meaningful and that would be very difficult or impossible for most humans to create with their hands," and will get a work of art that is, in blinded assessments, competitive with the work of any master.

If that happens, I agree that the top 100 human artists in the world will likely have jobs, but they won't be successful in the sense that their work is uniquely valued by society. We pay to see the very most talented humans perform tasks that have been successfully automated, such as chess and lifting heavy objects, not because we need the service they provide but because we get an emotional kick out of seeing other humans perform way outside the normal range of human abilities.

I’m willing to bet money it will never happen. People said the same about self-driving cars, but the initial razzle-dazzle blinds people to the actual dullness of the algorithms, and obscures their limitations. AI can only recombine what has already been created. It has no ability to imbue art with meaning or to push the medium forward.

What you describe can only happen with general intelligence, not these fancy neural nets. If anything, they will become powerful tools to help artists augment their creativity.