We still have Syria and Iran to deal with. Lets not assume when Iraq is peacefull the rest of the mid east will be.Yes lets bring more troops. Lets finish this War on Militant Islam.
Iran is just waiting for Iraq to be free. They will overthrow the gov't as soon as they think they can get away with it.
Syria and Saudi Arabia will follow shortly. They'd rather control the transfer than be overwhelmed by it.
Iraq is the key.