When you think of the content of the books in Baldur's Gate and the sheer amount of human hours poured into something just to give background to the game, this is going to save indeed a lot of time.
But on the other hand, just like open world was a terrible curse with hundred of games feeling empty, I'm afraid we will see a wave of games with a lot of generated but eventually uninteresting content because this is so easy to do.
After all, good content is coherent, and filtered. It's not just about producing a lot, it's what you don't put in the game, and what you do to glue things together.
I sure GPT will eventually be better at it than humans, but for now, having a human veto is necessary to have a good noise/signal ratio and because GPT is "good enough", being lazy is tempting.
But yeah, I can confirm GPT4 is already quite good at it and will only improve from this point.
This is going to be very interesting years.
Edit: I just made it write a full video game scenario, using BG as a competitor for basis. At first it was average, but with directions, it refined it and became quite good. Some kind of steam punk guild called the Navigators reading the wind, living in floating islands and a girl rediscovering the earth bellow the clouds and rebuilding old aliances with lost civilizations, plus a politician leader trying to prevent that and even a mentor to help her. Not bad.
I would play this, and even read it.
You can see the inspiration from "The Pillars of the Earth", "Gunnm", "Baldur's Gate" and "nausica" proving again it's mostly assembling known stuff.
But a cake is mostly assembling known stuff and it's still good. The "last of us" is just a good take on something that has been done a thousand times.
So why not?