Regardless, the human generating and publishing these images is obviously responsible to ensure they are not violating any IP property. So they might get sued by Disney. I don't get why the AI companies would be effected in any way. Disney is not suing Blender if I render an image of Mickey Mouse with it.
Though I am sure that artists might find an likely ally in Disney against the "AI"'s when they tell them about their idea of making art-styles copyright-able Being able to monopolize art styles would be indeed a dream come true for those huge corporations.
1) the artist is not literally copying the copyrighted pixel data into their "system" for training
2) An individual artist is not a multi billion dollar company with a computer system that spits out art rapidly using copyrighted pixel data. A categorical difference.
On 1, human artists are copying copyrighted pixel data into their system for training. That system is the brain. It's organic RAM.
On 2, money shouldn't make a difference. Jim Carrey should still be allowed to paint even though he's rich.
If Jim uses Photoshop instead of brushes, he can spit out the style ideas he's copied and transformed in his brain more rapidly - but he should still be allowed to do it.