Assad is certainly not our friend. He has worked consistently with our enemies against us, and he has kept Lebanon under his boot heel.
But what we have is essentially a corrupt balancing act. If he goes, then we will get the terrorist fanatics themselves in charge. I don’t know if that’s better.
I certainly wouldn’t do anything to defend him, but we would be VERY stupid to help his enemies and get involved in yet another war.
Let them batter each other bloody. Whoever takes over will not be a friend of Iran or Hizbollah, because the majority of the country is Sunni. The lesser of the two evils is the devil we don’t know. The Kurds might conceivably be friendly, should they gain some territorial concessions through the agency of the US.