Where you have a substantial Islamic minority, the only stable solution is for Islam to rule or to be violently and brutally crushed. Nothing in between works, despite over a thousand years of governments, peoples, cultures, and religions trying to find something in between, and endlessly failing. Where you have several different substantial Islamic factions in a single country, the only solution is a brutal dictatorship to keep the Islamics in line. That, or genocide. It is the nature of Islam to make war till it conquers or is very thoroughly conquered. Very thoroughly conquered.
Aleppo is about to fall. The fall of Aleppo will be the defeat of the “moderate” (“Christians to Beirut, Alawites to the grave”) opposition.
The difference between the “moderate” opposition and Islamic State is not their position on Christians and Alawites. They both intend to kill every Alawite everywhere. It is their position on the royal families of Jordan and Saudi Arabia. The “moderate” opposition supports and is supported by royalty. Islamic State is republican and intends to overthrow the royal families. Thus the defeat of the “moderates” is likely to cut off royal aid for the overthrow of Alawite rule in Syria.
The “moderates” are at present transferring large amounts of American and Saudi military aid to Islamic State, with a wink and a nod from the State Department, making the war in Syria a major profit center for Islamic State. With the defeat of the “moderates” Syria becomes a cost sink, so Islamic State (which needs to make war pay) will retreat, likely under cover of some face saving formula that pretends Islamic state is not defeated, pretends that Sunnis are not being ruled by Alawites, and pretends the State Department has not suffered a humiliating defeat.
The Pentagon, the red empire, the empire of the bases, supports the royal families of the Middle East. The State Department, the blue state, the empire of the consulates, opposes the royal families of the Middle East.
Putin will be reluctant to humiliate America by rubbing it in the way America was humiliated in Vietnam, since that is likely to destabilize the world, and will therefore try to maintain some pretense of Sunni autonomy. On the other hand, the American government is getting aggro, responding to its defeat in Syria by pushing for war with China, much as Hitler, when up to his neck in alligators, declared war on America.
Thus while Putin would likely favor some compromise that allows the State Department to save face by pretending it is still destabilizing Syria, the US, to judge by its behavior towards China, is not in the mood for saving face, but rather, believing that history is on its side, wants victory and to be seen to be victorious, where victory means at minimum maintaining Syria a chaotic bloody hell hole, with the final objective of expelling the Christian minority and exterminating the Alawite minority, thus making possible a “Democratic” Syria. Democracy requires a Syria with a single religion, Sunni, and a single ethnicity, Arab, and the State Department has repeatedly demonstrated that it so loves democracy that it is willing for other people to pay the price.
There is a significant risk that the State Department will regard peace, stability, and order in Syria as an intolerable affront, and will do something drastic to ensure that history proceeds as it is supposed to.
The American government is now spiritually in the same position as the Soviet government used to be. It believes it is destined to rule the world, being the voice of truth, light, and history, while it buggers its economy and its technology stagnates, undermining its power to rule the world.