The issue isn't objective quality or realism, it's sticking to a specific style consistently.

_Everyone_ (and their grandmother) can instantly tell a ChatGPT generated image, it has a very distinct style - and in my experience no amount of prompting will make it go away. Same for Grok and to a smaller degree Google's stuff.

What the industry needs (and uses) is something they can feed a, say, wall texture into and the AI workflow will produce a summer, winter and fall variant of that - in the exact style the specific game is using.

If we're talking about texture upscaling alone (I suppose that's what the parent comment means), Nano Banana is a huge overkill.