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.
We might be able to argue that the computer program taking art as input and automatically generating art as output is the exact same as an artist some time after general intelligence is reached, until then, it's still a machine transformation and should be treated as such.
AI shouldn't be a legal avenue for copyright laundering.
Automated transformation is not guaranteed to remove the original copyright, and for simple transformations it won't, but it's an open question (no legal precedent, different lawyers interpreting the law differently) whether what these models are doing is so transformative that their output (when used normally, not trying to reproduce a specific input image) passes the fair use criteria.