Syria after Assad
not my area of expertise, but...
What do I know about Syria?
It is not ready to become a democracy. North, Weingast, and Wallis describe two forms of order: one is the natural state, in which violence is contained by having the violent groups form a coalition to rule. The rulers exclude everyone else from forming large organizations, either political or commercial; the other form is an open-access order, in which anyone can form a political party or a corporation.
Syria does not have the background conditions or institutions to be an open-access order. If Syria attains any stability at all, it will be as a natural state. But I am not sure that a stable coalition can be had there.
The forces that overthrew Assad are strange bedfellows. They include Kurds as well as forces backed by Turkey, which is very anti-Kurd. They include gangs and militias of various ethnicities, religions, ideologies, and personal followings.
With Assad gone, the basis for unity among the rebels is gone, as well. Now their ethnic and political divisions will be exposed.
This reminds me of descriptions of South Vietnam in 1963, after the fall of Diem, in a coup encouraged by the United States. Once Diem was gone, the fractiousness of the South Vietnamese came to the fore. The infighting and coups continued throughout the period when America was trying to help them fend off the Communists. You can argue that we won the war, but regardless we lost the nation-building exercise.
Syria has too much strategic importance in the neighborhood to be left to the Syrians. Turkey, Iran, and Israel all have vital interests in the country. The phrase “spheres of influence” comes to mind.
At minimum, Israel will want to see that Syria does not become a sanctuary or staging area for Hezbollah or other militants. At minimum, Iran will want to see that Syria does not become a sanctuary or staging area for opponents of the Teheran regime.
Turkey will probably be the strongest player in Syria. Erdogan probably has the ambition to make Syria a Turkish satellite, and if so he has the military capability to do so. Israel and Iran might tacitly approve, provided that Turkey meets their security needs.
Those are my amateur guesses.
“Syria” was one of those post WWI “countries’ created by Europeans with a map and a crayon to draw borders for their convenience/profit. Consequently, it has no unified citizenry, only fractious tribes and ethnicities and religions that have been held together by force and force alone. It will now devolve into balkanization . . . or more likely wind up as a "natural state" held together by a new central force or uneasy coalition of forces. It will become naturally what our U. S. and European leaders are trying artificially to force on their countries–warring tribes that must be controlled by force from the central government. Sensible people would prefer that central force not be controlled by Shia Iran or Sunni ISIS; Israel is doing its best to keep that from happening. Surprisingly enough the USAF also seems to be on the side of reason. Perhaps because we do not have a President right now, so somebody is acting sensibly for a change.
You don't mention Saudi/UAE, which is the other major external force involved. The interesting thing is that Israel, Turkey and Saudi all have similar interests in Syria, and have all been able to get along well at times (albeit not right now) so maybe that is cause for some cautious optimism.