tl:dr 100 pages: 1) People are fucking poor and hungry (extreme wealth inequalities) 2) Salafi/Wahhabi (Saudi) funding of islamism 3) Antediluvian hatred between people (it goes, way, way, way farther back than Sykes-Picot)
Do you think Saudi will fall apart?
Besides that, it is a regime, and really, a nation, that is entirely predicated on petro-dollars. They have been fighting a price war against US/Canadian oil production, burning foreign currency reserves, in the hopes of setting back the clock. Unfortunately, the break-even point in the North Dakota and shale oil fields keeps going down[1].
[1] http://www.forbes.com/sites/rrapier/2016/02/29/the-break-eve...