Unfortunately, there is no roadmap or anything similar. The only source where you can sneak a peak to some planned features are Developer blogs, which TW were releasing before the EA came out.
Not really, the purpose of bannar in the battle field was mostly to help the troop to understand what is going on in the battlefield and even telling them what to do. When a reinforcement arrived at the battlefield, no one would know whose side this reinforcement was belonged to, unless a scout reports that it;s xx lord's banner. But a moral change would be pretty practical since the AI don't use visual banner to identify who is the enemy and don't need banner to understand the given order such as F1+F3.
I tried a banner mod once, but it only adds banner to the troop's inventory, which sucks. I wish the banner could be a decoration added for the spears and lances. rather than just an off-hand item that don't do anything in fight and take away the ability to carry a shield or to wield a 2handed weapon.