One of the first things Obama will need to is get out of Iraq. Not only is this required if he decides to double down in Afghanistan (something I’d recommend against) but the cost of the Iraq war is no longer bearable. The problem with getting out of Iraq is going to be all the hand wringing from the usual suspects, either about al-Qaeda, or about the possibility of Iraq not being stable without Americans there. While it’s true that Iraq isn’t stable with Americans there, and that everything is being held together on the one hand by Americans paying protection money to the Sunnis not to get uppity and on the other hand by Iran tamping down Shia disquiet, it’s also true that there’s some potential for destabilization.
One of the biggest problems is Maliki’s perception of his own strength. Folks like Visser and Eric Martin have been arguing that the central government’s increasing strength means it thinks it can survive without the US. Combine with Iranian pressure to get the US out, and stupidity like the raid into Syria; add in a dollop of general Iraqi hatred of the American occupation, and you’ve got the unwillingness to sign the SOFA. Iraqis want the US out, and no longer fearing that much for his life and power without the US, Maliki is willing to go along.
The problem is this: I’m not so sure the Sunnis and Sadrists perceive Maliki’s power as being as great as he seems to think it is. Yes, he’s built up a very nasty security apparatus. Yes violence has declined due to the demobilization of the Sadrists, paying Sunnis not to fight, and due to ethnic cleansing mostly having been completed. Yes, he’s got a big military. But that military has never performedl against the Sadrists without US help. My suspicion is that it’s paper, and will fold under the least pressure. And "demobilization" of Sadrists doesn’t mean much. They’re a militia, and Iraq is awash with weapons. If his people back him, Sadr can whistle them up pretty much whenever he wants to.
Likewise, the Sunnis of the Awakening councils have spent the last couple years being given money, training and weapons by the US in exchange for not shooting at Americans, and for shooting at al-Qaeda in Iraq. When the US leaves, that money will get cut off, but they’ll still have the weapons and training. Cutting that off is actually one reason Maliki probably wants the US out—"please stop arming my enemies." However Maliki will have a choice of either paying them himself, or of trying to crush them. And maybe they’ll decide they can get more with guns than he’s willing to offer.
The great peacemaker, the force pushing Iraq to be stable, is Iran. Iran wants a friendly government in charge of a stable country. Maliki is friendly, and they will back him if they think he can win. They don’t like Sadr nearly as much, though they can do business with him, and they definitely don’t want the Sunnis back in charge of Iraq (that whole Iran/Iraq war thing).
All of this is worth considering, but should be largely irrelevant to US decision making. At the end of the day, the only people who are going to make Iraq stable are Iraqis, with the help of their close neighbors who have a real interest in their stability. Americans are exacerbating internal tensions, especially Sunni/Shia tensions, even as their muscle ensures that no one can succesfully militarily challenge Maliki. But until Maliki proves he can survive without US help, or fails, there can be no real stability, because there has been no real test of power.
And, perhaps more to the point, the US has other fish to fry. The money being spent on Iraq can be better used either helping the US economy (frankly, a greater security concern than Iraq at this point) or perhaps in Afghanistan (as noted, I don’t think Afghanistan is "winnable" anymore, but if you do, then that’s an argument to pull out of Iraq). Most of whatever gains the US can get in Iraq have been achieved. If after all these years and all the money and training Maliki’s army can’t win against its internal enemies, another couple years aren’t going to make a difference, especially as the issue is not guns and money, but esprit de corp and morale. And morale will improve massively when soldiers don’t think they’re fighting for an American puppet government.
So, while acknowledging the risks, it’s time to leave. The elephant in the china shop has done what little it can to fix the situation, now it’s up to the people who work in the shop to finish the job as best they can. One of the lessons the US still needs to learn is that "it’s not about you". Sometimes you just have to let other people take care of their own problems, and not interfere.
And, more to the point, sometimes you need to tend to your own affairs. This is one of those times.