Here are my answers. There are no good guys in Syria, and even if with US assistance Assad was overthrown, it would not end the civil war, which would just devolve even further into a multi-sided hell that makes Libya and Iraq look like a picnic; it would empower jihadists who will slaughter as many or more as Assad has; the flow of refugees will not stop, although the composition of the refugees might change (with Alawites and Christians replacing Sunnis); if the opposition gets control of Syria, it will be the jihadists who control the opposition, and Syria will become a base for anti-American and anti-Western terrorism.
Syria is even more broken, complex, divided and fissiparous than Iraq was/is. It is rooted in the same political and religious culture, and the same civilization.
Minority-based Baathism has had 13+ more years of power in Syria. So what has happened in Iraq in the last 13+ years is probably the best scenario in Syria. And I would consider even that happy prospect to be among the least likely.
And one more thing. An American intervention in Syria would risk a superpower confrontation. Even a unicorns and rainbows outcome in Syria would not make such a risk worthwhile, and as noted above unicorns and rainbows would not be the result–a dystopian, sectarian war of all against all would be. And the US should be in the middle of that why, exactly?
Emphasis is mine. I share Craig’s view: “Reforming foreigners isn’t our business”. We should support no “democratic” opposition, no “European aspirations”, no “liberation from oppressing regimes”, no “anticorruption forces” – be it in Syria, Ukraine, Russia, Belarus, or elsewhere.