I am hoping for an increased "court interactions" expansions. There would be an influence system where various courtiers would be able to influence the monarch to do what they want. If the ruler is weak and, say his wife or a favourite courtier has great stats, that person would gain enough influence to become a regent and rule in the king's name. There would be schemes to put people on the council (the person with most influence on the ruler would try to put their favourite people on the council).
It would make the game more interesting. Not only would you have to worry about external enemies and factions within your own Kingdom, you will also have to worry and manage shenanigans in your own court...
ed: Or, may be I have been reading too much Game of Thrones lately...