The thing is, the war isn't over. The combat mission of the United States Army has come to an end, but the war isn't over. There will still be thousands of troops there training the Iraqis as well as special forces continuing raids.
This is the exact same thing as Bush's famous "Mission Accomplished" speech. In fact, he said the same thing, that major combat operations are over. Well in a sense he was right; in another sense, also known as reality, he couldn't have been more wrong. We ended our attack but combat operations weren't over, as we've seen over the past seven years. Now Obama is saying the same thing, just from a different time frame and different circumstances. We're simply reducing our footprint in the region, that's all. There never, ever will be a complete pullout of Iraq. People think that we're just going to up and move all our forces home. We didn't in Italy, Germany, Korea, or Japan, so why would we leave Iraq? It would be a great idea on a personal level but on a geo-political level it would create a power vacuum eventually.
The Iraqis will pretend to get along with each other until someone insults someone else's 4000 year old retarded tradition, which will spark another civil war and the US will have to come back in to play peacemaker. No, it would be much more cost-effective to simply baby-sit them with a small military presence for the foreseeable future and give them the illusion they are able to stand on their own. Eventually we may be able to completely pull out, but not in our lifetime. The only way we'd leave is if the government kicked us out like the Saudis, but then they'd be cutting off their own foot. These people wipe their asses with their bare hands, do you really think they can run a modern, secular, and civilized country?