Hmm.... Iraq.

Things can be made right in Iraq wihout the U.S. presence, but that would involve killing a whole bunch of people. As much as Sunnis and Shias hate each other's guts, they hate the Kurds even more. To make things even more complicated, Sunni Kurds hate Shia Kurds, and everyone hates the Yezidi Kurds. And of course there are Christians caught in the mess powerless to do anything. When we leave, we should take the Christians with us. Kurdistan can be pressured not to secede, and it will be wise for them to maintain the status quo. I'd hate to see another war break out there, considering that it's actually a functioning democracy, and I'd hate to see that go up in flames. As for the rest of Iraq, it'll depend on whether Kurdistan secedes. In the Kurds stay put, and our boys are out of Iraq, most of the local crazies would lose whatever popular support they might have now. As long as Shia government doesn't crush too many toes and treads lightly when it comes to Sunnis, Iraq should see some improvement in security.
Now, if Kurds decide to break free, it'll definitely unite the Arabs. Arab military who will be *eagerly* aided by the Turks (and porbably by Iran as well) will move in, crush the Kurds on two (possibly three) fronts, and revert Iraq back to a unitary state. has too many enemies to make it out alive as a free state.