In a rather revealing Q&A with Ozan Gümüş, the Campaign AI Programmer working on Mount & Blade 2: Bannerlord, TaleWorlds have gone into considerable detail on what may well be considered one of the most important jobs in developing this type of game.
In short, Gümüş works on balancing, optimising and tweaking the way in which the entirety of Bannerlord's gameplay mechanics interact with one another, because the main way in which this sort of interaction is accomplished lies in the way that different types and levels of game's AI interact with one another.
According to Gümüş, Bannerlord is first and foremost a complete and total sandbox for the player to explore and play around in. As was the case with most previous Mount & Blade titles, players will find themselves thrust in the world of Bannerlord with no particular goals other than the ones that they set up for themselves, and the fun of playing this game will come from exploring the ways in which players can affect the way that the game world functions, practically speaking.
Interconnectivity is key, and the central axis upon which the rest of Bannerlord will operate, because each and every of the game's systems and mechanics will affect how others work, even after the unknown that is the player character begins interacting with them.
Since the majority of programming is already in place and waiting for the rest of the polish to come into its own, Gümüş is now working on balancing the game's economic systems and fixing bugs, which might make some of us hopeful about Bannerlord's long-awaited release. No information on that just yet, but do stay tuned, as per usual.