it's basically just a really powerful brush helping you to translate your thoughts to a canvas more efficiently. What the art contains, the artstyle, composition, colors etc are all still decided by the artist.
I think the biggest effect of AI will be that it will increase the scale of art. Instead of doing a paintinf a year, you might be creating a city sized art piece a year.
Basically artists will transistion to becoming more like art directors.
Projects that are done with potentially hundreds of people today (like a movie or a video game), might be done with just one person. And future projects with hundreds of people will instead have 100 times the size/detail.
You're basically taking the manual labor out of art, but not the art out of the art.