Financially, well I'd expect people as an aggregate would keep spending about the same amount of money, so I don't think the proverbial pie would get any smaller, though it might change who gets a piece and how large that piece is.
Guess what, such is life! Even if we, for the sake of argument, imagine that the existence of such an AI is 100% guaranteed to render me personally unable to make any money whatsoever from making games, that's a price I would be willing to pay! I'd have to work with something less fun but I'd keep making games in my spare time just for fun anyway.
It's not like making a living from our passions is some god given right, It's a privilege! And if that privilege is the cost for making my passion more accessible to everyone, that's a price I'd pay in a heartbeat. I can't wait to make reality out of all my ideas, and I can't wait to see what others are going to make with it either!
It's already one of my bigger regrets that I don't contribute more to open source resources that would make game development easier for others, I just can't find enough time and energy for it.
From the consumers perspective, I expect there'd be a lot more to choose from. I imagine the quality of indie games would rise immensely. Heck gamers could even just use the AI to make a custom game tailored for their own tastes from home, how sweet would that be? Might that make the pie smaller for pro Devs? Sure, it might, but who cares! It also might not! Who knows?
The one thing that is guaranteed from such an AI is that awesomeness goes up. I want it!
I am a creative type that became a commercial SE to actually fund my lifestyle. I don't expect to just make money from creative hobbies just because I want to, so I have gone for a job that is in high demand. But AI will eventually learn to code well enough. Then there will be no demand for software engineering, one of the few job markets that even has this level of demand and high employment. So what's the next avenue for us when that job becomes obsolete.
I've worked hard to be where I am too, but if you, like me, were able to land a software engineer job, you'll be able to pick up whatever new skill will be needed in the future without much trouble! I have no doubt you'll manage, so I don't worry about it!
If AI leads to ALL jobs being automated well guess what, we're ready for Luxury Gay Space-Communism as described in Iain M Banks' The Culture. My personal favourite sci-fi utopia!
I wouldn't hold my breath for that though, seems about as likely as running in to Jesus Christ in the supermarket. And I say that as an atheist.
