Marc Lynch poses a question:
What does it mean that no Kings have thus far fallen in the Arab uprisings while four non-monarchical rulers (Ben Ali, Mubarak, Qaddafi and Saleh) have toppled from their (non-royal) thrones and a fifth has plunged his country into a brutal civil war?
His answer:
Access to vast wealth and useful international allies seems a more plausible explanation for the resilience of most of the Arab monarchies. Surviving with the financial resources and international allies available to Saudi Arabia, Qatar and the UAE seems like no great trick. The active, concerted economic, political, media (and occasionally military) Saudi and Qatari support for their less wealthy fellow monarchs seems to be more important to the survival of the current crop of kings than the intrinsic institutional characteristics of a throne.
The Dish 