There's no doubt that when Bannerlord releases it will be superior to Warband in every way possible. Based on the forum posts, videos, and other commentary on the game we've seen/heard/read we know it's practically a graphically-improved, engine-improved, and feature-improved Warband, which is much needed and I can't wait. But my question for the man working on the campaign is this:
Will we see a co-op campaign?
It's been asked before and I know it'll be hard due to the world going to have to be CONSTANTLY running (time will always be passing), but I think it should be added if possible. You can make it so that the host of the "save" file has the master control of the "time" and can pause the server at any time. As for battles/sieges/"strolling through town"/inside castle doors, make the world map time suddenly pass by in half (or whatever percentage the map battles take) and have a message come at the top of the screen saying "<player name> has entered a battle." The "wait here for some time" would pass at normal map speed rather than super fast, unless the all players, including the host, is waiting for some time or using "ctrl+space" also.
Mainly the reason why i want to see this is because I want to play with friends and we've already talked about how if those features above were made true, we'd deal with it. On you guys' end you could have a pop-up menu come up when they press "start new co-op campaign/join co-op campaign" that warns of the host being in master control of the time. If they don't like it, then they won't play it. They'll just stick to singleplayer, which is perfectly fine. The people that want this feature of a "co-op campaign" know it's played together, where you're already talking to each other LAN or using some internet-based voice chat program.
Of course, there are a lot of features that would need to be added when it comes down to interactions. Such as, who has commanding authority, etc. but those features wouldn't be hard to add in my opinion as you'd have to just brainstorm all the events one person could take by themselves and ask yourself how would another person influence that event.
Thanks for listening, I'd love to see this in some way. At the very least have some way to where a "random stranger volunteers to join you army for no wage" pop-up comes up and your friend(s) are now in your party able to see the world map and watch what you do. This way they can just communicate together where the party should go next, etc.