Sorry. Although I agree we can't leave Iraq in the condition it's in now (especially since it's been American policies since 2002 that have created this mess in the first place), I can't hang idealistic goals and good intentions to the effort either. We need to stay, because should we pull out altogether, and the region collapses under all the power plays going on, then all the western economies will collapse under $150 per barrel oil prices.
Planting the seed of democracy in the middle east was arrogant and short sited on the part of us Americans in regards to the social-political realities that is the middle east. For democracy to take hold, there would need to be a national identity.... there is no national identity in Iraq. They do not see themselves as Iraqi so much as they see themselves members of their religious sect, clan, tribe, or their power base in relation to others. That's were their loyalties lie.
I know the official grand plan was to spread the joy of Democracy (ironic, since we've been sliding from a Republic to a Oligarchy for years now), but that was an unrealistic goal from the beginning.
We'd have been better off chasing al Qaida to the countries they fled to from Afghanistan: Pakistan, Philippians, Indonesia, Bangladesh, and so forth to keep them hounded and off balance rather then allowing them to regroup, reorganize, and retrain unmolested. That's not what we did, and we have to pay for those mistakes in treasure and blood.
It has not just been al Qaida causing terror and trying to break up Iraq. Everyone has a stake in the power play in the region. The Arab countries would benefit from the Sunni's coming out on top. The Persians have an interest in the Shii coming out ahead. The Turks seem to be getting over their distrust of the Kurds and developing ties to them and their region. Syria has no interest in closing it's borders to allowing it's own troublemakers to cross to Iraq to make mischief. The Sunnis are trying to hold or regain the power they once had. The Shii want to take revenge on the Sunnis for decades of oppression. Iranian arms smugglers enjoy the business opportunities in Iraq, using the same smuggling routes that Iraqis use to deliver alcohol and porn to Iran.
This was never about bringing liberty to Iraqis. This was about geographical location. The dream was a democratic Iraq, in the middle of the world's primary oil regions, in which to permanently locate American military bases from which to project power and influence over the region. It was seen as a middle east version of South Korea. It was about gaining direct access to Iraq's oil. It was about turning a democratic and western friendly middle east country into the front line of the "Long War" and keeping it away from America's shores. But, due in a large part to very stupid decisions made along the way by American leadership, the effort has so far failed and ground down to what we have now.
We can't realistically pull out, without huge consequences. Those in power are unable and unwilling to come to grips with the mistakes that have been made to date. And I'm not sure there is the political or national will to see this whole mess through to at least an acceptable conclusion.
About as close to a no-win situation as I can think of now. It's now down to salvaging as much as possible and lose less badly. So, although I agree with the "can't win" sentiment, we can't leave.