It is apparently time to celebrate the good news in the Middle East. Bashir Assad has been toppled in Syria; he and his family have fled to Russia, and there is a power vacuum in Syria at last. We are told this is good news. With the dictator gone, the Arab street is full of joyful revelers, waving their automatic weapons in the air, hoisting their flags, cheering the coming caliphate. Good news. Party like it’s 1999, as they say. But there’s a problem: We don’t know for sure exactly what’s coming next. This isn’t like a baseball or football...