That artists will be able to do more not necessarily mean that fewer of them will ne needed. I bet the opposite actually. Companies will want to produce more (with more resources) not the same (with less resources).
I guess a better way to rephrase that: would it make them more profitable to produce more art? Or to keep producing the same amount but paying fewer people to do so?
When something becomes much cheaper than it was before, people tend to find much more uses for it. In game development, for example, amount of money that could be spent on art almost always amount and quality of content; if art becomes 10 times cheaper, a typical indie game will have 2 times more different pieces of content with 5 times variants of each.
But now the situation is bit different, coz there's a limit to the number of pieces before it looks awkward and that limit can be reached by AI generated contents quite easily and quickly thus not needing to have more man power.
On social media and elsewhere, companies need more and more varied content on a daily basis. Many are effectively now producing something akin to a magazine or a TV show to stay present in feeds or minds.
