Whomever manages to unify* Arabia under a single Caliph, thereby reconstituting the old Arab-run Caliphate of 1000 years ago. Only now, he'll have something better than the now-defunct caravan routes between the Far East and Europe that once provided a steady income - oil. And he will have Arab nationalism as well as Islamism as the glue to hold it all together. Maybe Morsi, maybe some other Muslim Brotherhood or Salafist figure.
Arabia has spent almost 1000 years under the yoke of various Turkish overlords. The idiots who make policy are hurrying its unification along. Does the West really need a massive unitary adversary on its borders? Isn't Russia a big enough threat?
* Unlike Saddam, Islam's Lenin will already identify with the troglodyte that is the Sunni Arab man on the street. In Kuwait, Saddam had to conquer and kill these troglodytes. Islam's Lenin will back them with money, arms and training to overthrow their overlords, the Gulf royalty. The difference between Assad and the Gulf kingdoms is that Assad's elite forces aren't filled with Islamists. The Gulf kingdoms are nothing but, which means they will be loathe to fire upon masses of Islamist demonstrators interspersed with armed insurgents when the time comes.
Nobody is ever going to unify Arabia under any caliph. Why do you think the Saudis support the rebels, because they want al-qaeda to overthrow them and establish a cliphate? Wrong. That will never happen. You think the King of Qatar wants to be overthrown by a caliph? Pure fantasy.