I recall at least two speeches by the President both prior to the interim government's elections where he told the American public that we'd be there for several years and has usually talked about "staying the course" and the "long haul". I think no one pays attention and if they do it's considered a "bad thing" to have to commit forces to a multi-year mission. This has resulted in a rush to turn over the security mission to hastily formed, poorly vetted, and less than thoroughly trained Iraqi forces. And while they're certainly taking a heavy load, I worry that too little time for training in not just tactics but in dealing with the civilian populace especially among the non-Kurdish Sunnis in the country which may lead to abuses that could result in something similar to the "Vietnamization" of that war where the local forces collapsed before a highly trained and experienced enemy. One of the things about an insurgency, is that it is very fluid. Right now, we're way on top of them and forcing them to be defensive and to have to resort to terrorizing the local populace in order to maintain even a subsistence level of support. But that could change tomorrow should something come up that increases popular support for the enemy. So timelines are meaningless and there is no linear or geometric progression. This is why this kind of warfare is often referred to as being "asymetric" by tacticians.