I don't know yet. Let's talk about it, shall we?Speaking about decadence: what mecahnisms will Muslims get to ensure that dynasties can rise and fall more easily than in Europe? A simple kludge would be to give the regent, the grand vizier and the 3 biggest vassals or so a strong claim on the liege's title during regencies, and perhaps increase the propensity of Muslim rulers to form factions pressing claims. A more sophisticated system would be to set up specific factions that demand a new ruler from their midst or a fracturing of the realm...
General Objective: Make Muslim blobs less stable. Make it more fun to play as a Muslim vassal to, say, the Seljuks. Perhaps, find a mechanic which tends to lead to dynastic churn, possibly realm fracture, and then probably expeditious realm reunification / cleanup of the border gore (could be into smaller kingdoms).
All turnover is generally assisted by dynlevy, our short name for the dynamically-scaled-with-realm-size liege levy feature that applies to all rulers (including vassals) and the design of the levy system in EMF generally, which rapidly depletes the liege levy while leaving vassal subrealms full of troops still ready to go. Further, EMF's independence faction is far more rowdy and capable of actually breaking a realm apart (woe, the border gore!).
We do have a system in the works for turning proven, landed military commanders into political threats. Not sure how that would help with these specific goals in the Muslim world, besides more wildcard factor and a pretty good chance of a player marshal in an empire eventually earning a strong claim on the throne.
I am less interested, though, in abusing claims to promote instability generally. It's not terribly plausible. Custom CBs and/or factions are, however, a potential solution. If you had that at your fingertips, what do y'all think would be plausible casus belli mechanics for dynastic turnover and potentially the rise, fall, and expeditious reunification of large Muslim realms?