The amount of mercenaries you can have will probably get expanded to around 20-24, while the number of mercs that you can field will be lower than that.
Actual ranks probably won’t get added. You can already do something akin to that with the utility tree perks, though.
Being able to reorganise troop order will also get added.
Those are very good ideas, it would be great if we could have these options!
Also, another thing about recruitment: when you dismiss a brother, the tooltip says that he will remain in town for a while if you decide to get him back. However, that doesn’t happen and you kinda have to save scum if you ditch a brother to get another with better past, but end up getting screwed because he has crappy traits (perhaps if we could check traits before recruitment would be nice too).
They stick around? I wouldn’t know since I’ve never fired anyone. I almost never have a full company, because I keep sending rookies on test runs. Could be that that’s a placeholder for a feature that has yet to be added.