Assad leaves, that means his tribe, the Alawites get slaughtered.
Their numbers have been reduced considerably. Some say 1/3 of fighting age men. As bad as things have been in Syria, they will only get worse.
Assad is going to go; what’s left of the failed state of Syria will continue to be cut up into little meatballs, just like Lebanon and Iraq — and the common denominator is Iran, which is the only foreign power occupying territory in any of the three. In perhaps twenty years, after the open warfare simmers down into a grumpy, slightly violent coexistence, a patchwork of paramilitary pseudostates, each run by some Arab warlord, will control everything that is now considered Syria and Iraq, with the exception of Kurdistan. Alas, I doubt that Kurdistan will have international recognition as an independent state even by then.