So to summarise the above, here is what I understand:
1) Density needs to be reworked (and/or bring in Hinterlands) to enable greater territory conflict in a meaningful way. I.E. enabling a realm to attack it's neighbor and to take a city for example.
2) To enable the above, redesigning the estate system to accommodate a greater spread of nobles across regions but allowing "tall" to still exist.
3) Overarching alliances and *pile ins* are human instinct and difficult to stop. Therefore, providing incentives to prevent them forming out of choice or allowing them to collapse can be a step in the right direction.
4) With the above, changing how war works will support dynamic politics. One great idea is for terrain to impact battles, such as width, bonuses to cavalry in rurals or even stronger siege equipment.
