I wouldn't care about reproducing existing building as long as the AI can generate credible ones in the same style, then place them on dynamic worlds created by prompting the AI. Having intelligent AI NPCs as long as AI generated scenery would be a killer feature in any game. I'm talking about off line disconnected single player games; cloud ones with these features could be already here, but I want to be in control, and marketing rules are against that: who would buy the new shiny V2.0 with the new worlds and characters if 1.0 could create them just by asking it to?
As someone who consumed tons of scifi novels and books as a kid and wants to be immersed in big worlds, enjoying great stories also in games (absolutely loved the Mass Effect saga), I already know what's going to happen when we'll be able to feed Philip K. Dick or Asimov, Sturgeon, Bova, Silverberg, etc. books to an AI and have it create worlds, environments, stories and characters straight out of the book descriptions. Literally drooling over it.