Obviously there's a focus on how LLMs will play into the main narrative... but what I'm more excited for, honestly, is how we can integrate them with NPCs and background narratives. An LLM could generate traits, backstories, narratives, etc for any number of NPCs; rewrite those narratives based on player actions when they encounter that NPC, or other related NPCs; use those updated narratives to create new NPCs, etc.
Very exciting times ahead in game design!