The area will descend into chaos. I consider this outcome quite real because that was the main goal of the powers which had started it all. A new politically unstable, dangerous region right under the borders of geopolitical enemies. The conflicts will go on, spreading hatred and poverty, making a good soil for various extremist organizations. Once again, the US will become the safest place in the world. By the price of safety in any other places.
Yet, I still hope we could solve that problem.