Currently the war is not buying much. A shift should be made to a lower cost approach. Just engage enough to prevent safe havens for terrorists. Redeploy to borders. Occasional sweeps through different cities. Reduce the objectives. Shore up allies Kuwait, Israel, Turkey, Kurds, Afghanistan, etc... Let Sunnis and Shia fight it out. Come back at a time of the US's choosing. A later unpredictable surge. Run experimental tech through Iraq. New UAVs, robot fighting systems, make things more unpredictable.
Put some of the money into research in game changing military sensors and technology. Re-engage when technology projects change the way things can be done.
Fareed Zakaria indicates the problem of the Arab states being mostly poorly run. The successful non-Arab muslim states of Turkey and Malaysia are examples what should be encouraged
Another Fareed Zakaria piece. Looking at our circumstances in Iraq should give us some appreciation for the difficulty of his [Kissinger's] task. With a losing hand and deteriorating conditions on the ground, Kissinger maneuvered to extricate the United States from a situation in which it could not achieve its objectives, while at the same time limiting the damage, shoring up regional allies and maintaining some measure of American credibility. A version of such a strategy is the only one that has any chance of success in Iraq today.