You don't need to wait for the LLM driven NPCs. It already exists and has been done for years. It's always, always, always absolute dog shit and doesn't add anything to the game. Voice acting is whatever trash the LLM puts out. You get the same roundabout sentences that LLMs put out.

Character customisation already exists. AI won't make blending textures easier or harder.

>game artists would change from making 3D meshes, textures and animations to being authors of storylines and styles.

You fundamentally misunderstand game artists if you think that the meshes, textures and animations they make _today_ isn't driven by a storyline and styling. That's the absolute core of everything artists do. Otherwise we'd have reusable animation packs everywhere, like every default UE5 game does and nobody would redo a 50th running animation.