However, few of the imaginable scenarios for post-Assad Syria portend stability after more than 17 months of blood-letting in a country that is more ethnically splintered than Iraq and holds perhaps the greatest international stakes of the Arab Spring.

One scenario: a bloodbath as Syria's majority Sunni population, which has led the uprising against Assad, seeks vengeance against the minority Alawite sect, an offshoot of Shiite Islam that forms the backbone of Assad's regime. The conflict's already increasing sectarian overtones suggest any power vacuum could usher in a direct fight between the two communities.

Another possibility is a free-for-all fight among the "victors" — the patchwork collection that makes up the anti-Assad revolt but has no common vision for the future. Among them are opposition figures in exile who have some political weight abroad but often haven't set foot