Heh, it would be definately kewl if a future release would feature duel of epic proportions (like "Revenge of the Berserk" mod, though staying on ground-level

). With foes who have 150-200 HP and armor values over 100.
I, for one, have many ideas regarding many aspects of the game, but until SOD v5.0 comes out I don't think there will be much time to work on them...
Some rough sketches:
At a time we were planning nobles/faith troops for the native Calradian kingdoms, but the limitations of vanilla MnB got in the way. In Warband, featuring such units should be no big deal.
More importantly, Calradians should have their own religious institutions (churches, sects, etc). The Player's choice of religion should influence diplomacy to some degree; ie, Swadian religion could be similar to the SOD religion of 'The One' -> +5 starting relation with Swadia, but -5 with, say, Vaegirs because of religious differences.
The player should also be able to receive quests from Calradian churches and thus earn relation points with the given Calradian kingdom; ie, hunt down heretics in return of increased relation, renown and some denars.
Diplomacy should also play a significantly greater role. It should be easy to anger other factions, and sometimes they could/should even team up against you, but at the same time it should also be easier to earn alliance with others. Tributes, trading alliances, peace treaties, military pacts, etc. - all are needed for a good medieval court drama.