I have a simple rule of thumb when assessing the potential instability of Middle Eastern countries. They come in just two varieties: countries that implode and countries that explode. That is countries where, when central control collapses, the ruined pillars fall inside its borders, and countries where, when central control collapses, the blast radius of the political shrapnel extends far and wide.
No country in the Middle East explodes more than Syria. Whatever happens in Syria will not stay in Syria.