I'd like to see a game that is the tabletop RPG to Mount & Blade's wargame.
In other words, a Skyrim-like FPS sandbox action-RPG that is not designed with looting dungeons and doing quests, but where the plot is treated as 'Here's the (suitably Fantasy Epic) situation we're dropping you in. You're not particularly special on your own, aside from your inexplicable ability to become World's Grandmaster in Things after a week or two of intense training. Now go do whatever, stuff will happen as a result of some things, or you can just go collecting daisies for ten hours.'.
So, join a faction, go beat up some opposing force dudes in a castle and capture it for a faction - yay, things happened. Fuck around 360 noscoping butterflies with a bow for a RL week but the same faction get a bunch of their own dudes to beat up the other dudes, same thing happens on its own. Decide all factions are dicks and go around exterminating garrisons and claiming it for yourself? Other guys send their dudes to take 'em back. This is just a basic example, it doesn't have to be so grand-scale like this.
It's more likely than not simply not technologically feasible, though Bethesda has actually been doing some of that work with the Radiant stuff in a way, despite it mostly serving to generate bland repetitive quests, but the concept of goal-driven AI is the way to go about it.