> The interesting question to me is: what happens when AI can not only implement but also playtest -- running thousands of iterations of your loop, surfacing which mechanics keep simulated players engaged?

Much the same as we do today in games and film both, something saccharine and mediocre built to appeal to a wide majority. Worse, if this process becomes streamlined and widely accessible, you're competing with a hundred other saccharine and mediocre built to a wide majority games. AI generated shovelware, it's like the shovelware of today where anything remotely popular generates dozens of cheap clones, but with AI.

The best games take risks and aren't min/maxed.