> been around for how long, and what serious professional game developers are using it as a core part of their workflow?

Are you in the game industry? If you’re not how would you even know they have not? As someone with some connections in the industry and may soon get more involved personally, I know at least one mobile gaming studio with quite a bit of funding and momentum that has started using a good deal of AI-generated assets that would have been handcrafted in the past.