The most recent dev diary focuses on what is going to be added in the free update "Castle" released along with Fate of Iberia. One of the changes is a new, global spanning, faction.
To model some of the big historical shake-ups in Iberia, developers have introduced a new faction type. The Dissolution Faction will aim to destroy the primary title of the top liege of the realm, as well as any other same tier title.
This makes all vassals independent, shattering a kingdom or empire. In FP2, this means that the Umayyads can collapse as they did in history, but it also means that any large realms in decline will face this challenge.
Anything detracting from a realm’s unity will increase the risk of a Dissolution Faction forming. That means short reigns, low cultural acceptance, war losses, and unallied vassals will all be dangerous to King and Empire tier rulers.
Realms where the vassals either like the heir or can elect their own are less likely to face a Dissolution Faction. And if a vassal can make a claim for the title themselves, they’ll do that instead.
We are yet to see how the Dissolution Faction will affect the balance of the game. After all, a new mechanic is only as good as the amount of abuse it can take from players before breaking the game. The way this is sounding right now, we can only imagine the border gore to follow.