Part of the reason I think it would be good to announce a timetable approximately now is precisely that it could be pegged not to arbitrary dates, but to scheduled elements of the political process, namely a constitution and the election of a permanent government.
This part seems wrong on the merits. True, it's almost a cliché by now, but defeating the Iraqi insurgency requires a political, not a military, solution. Everyone knows that. But let's not delude ourselves: some sort of military solution is also needed. As Anthony Cordesman has outlined in pretty painstaking detail, the insurgency has two components, but they aren't the two components people tend to think—i.e., a bunch of foreign extremists and a homegrown and mostly nationalistic insurgency. No, the homegrown wing has both nationalist and extremist parts, and the extremists continue to multiply, and almost certainly won't stop fighting until they are largely defeated. See Kris Alexander for what "defeated" would mean. This can only be done, I think, by bringing the native Iraqi military and police online, and doing it right, which will take time and patience. (Will Saletan's suggestion that the Iraqi security forces will get motivated real quick if the U.S. starts withdrawing and shoves them into action is, sadly, nonsense, and doesn't merit further discussion.)
In the past—again, up until about the spring of 2004—the training process simply wasn't working, and the Iraqi security forces often ran away from conflicts. All in all, a disaster. But since then, under Maj. Gen. David Petraeus, the U.S. actually seems to have restructured its training efforts pretty successfully. Iraqi police have now pacified Haifa Street, and have at least maintained a presence in Mosul—no small feat, either of them. American troops can withdraw, or at least become less visible, as this process continues, but not before then. Rushing the training component, or doing it poorly—for instance, by stocking the Army only with Shiite militiamen and Kurdish peshmerga fighters—would be a serious mistake. Without competent security, at this point in time Sunni extremists could very easily a) stage a coup in the parts of the military and police force that they have infilitrated, b) assassinate Iraq's leaders, including Ayatollah Sistani, and c) foment civil war by bombing Shiite shrines and the like. Easy. That's not the only way civil war could come about, granted, but I think it's the most likely, and a U.S. presence is necessary to avert this most-likely scenario until Iraqis can handle it themselves. If that point comes next year, fantastic. If not, then not. (And bear in mind, the Iraqi military, even as it gets up and running, will need U.S. logistical support for a good long while.)
As for the political process, Matt makes an important point: If Shiites, Sunnis, and Kurds want to fight amongst themselves once the U.S. leaves, nothing in the world can stop them. The U.S. should prepare for this very real possibility. On the other hand, it's not like all sides are so impossibly recalcitrant right now, putting the lie to Yglesias' statement that "[a] s long as we provide them with that safety net, they have no reason to compromise." Some elements of the Shiite coalition, at least, have been willing to make limited concessions to the Sunnis on their own accord. President Jalai Talabani has floated a wide-ranging amnesty for ex-Baathists, and the U.S. should overrule people like anti-amnesty folks like Ahmed Chalabi and encourage Talabani to do so.
As for the constitution: Granted, SCIRI-based Shiites like Abdul-aziz al-Hakim want to break up Iraq and form a Shiite super-province in the south, but in conversation, Andrew Arato has made the case that both Sunni groups and many nationalist and secular Shiites—including, it seems, Ayatollah Sistani—want a unified Iraq. The Kurds, meanwhile, want independence, and it's going to be hard to pressure them to accept anything short of autonomy. All in all, it doesn't look good—some near-intractable problems are at stake here. But unlike Yglesias, I don't entirely see how U.S. troops are "counterproductive to producing a political compromise," which is to say, I don't see all sides somehow becoming more willing to compromise if the U.S. starts drawing down. Again, setting a timetable is different from announcing, repeatedly and forcefully, that we will maintain no long-term presence there—the latter may convince more Sunnis to join the political process. Hopefully. I just don't see how the former will convince Shiites and Kurds to compromise more readily. Deep conflicts don't get resolved simply because the parties involved fear that they might have to go to war. History says otherwise.
More to the point, let's not kid ourselves. If Iraq erupted in full-blown civil war, the U.S. would have to intervene. Our oil addiction demands it. Pretending that we can just leave and wash our hands of the whole mess smacks of naivety. Iraq isn't some insignificant little foothold in the Balkans. I understand that civil war may happen whether the U.S. stays or not. On the other hand, the U.S. will have to micromanage the regional situation whether we start drawing down in 2006 or not. It's a real mess, but it's still real. We don't have much choice. Leaving now, only to be forced to re-invade three or four years down, would be the height of near-sightedness.
So what would I suggest? I'm very much open to persuasion, and much of this involves putting trust in a thoroughly incompetent administration, but my instinct is to go with Cordesman's bevy of small-bore recommendations, including: "Keep reiterating that the US will set no deadlines for withdrawal—or fixed limits on its military effort—and will support Iraq until it is ready to take over the mission and the insurgents are largely defeated." Keep pressure on the government to develop both the proper police forces and governing institutions, which won't likely develop on their own accord. Fix the aid and reconstruction process, which is a nightmare and the one prong of our strategy that continues to founder very badly. Sealing the borders may help, though al-Qaeda seems to be planning to take the fight to Syria next, so sealing the borders up could just accelerate that process. I don't know. Oh, and no more troops will be forthcoming, of course. The U.S. can still "surge" troops for specific needs, by fiddling with the rotation rates or reserves, but a major long-term increase in troops won't happen.
That seems like the rough outline of a realistic "plan," although I obviously can't guarantee it will work, and with this administration, it might be a go-ahead for "more of the same." But, I think, it's more likely to produce stability than pulling out prematurely. Feel free to convince me I'm wrong, because I'd like to be. Though I should also note that, in the event Cordesman's proposal simply can't work, then a withdrawal plus "hoping for the best" actually wouldn't be my second choice; rather, Daniel Byman's bloody-minded "Afghanization" plan for a draw-down seems, horrifically, like the most realistic and "stable" option. Meanwhile, the most important task here at home is to make sure that the crooks and liars who got us into this mess are removed from power as forcefully and quickly as possible. Iraq has been a colossal mistake, the sort the United States must never make again. That part, at least, needs no debate.
UPDATE: For a view along similar lines, see Retired Gen. Barry McCaffrey's assessment. Bear in mind, the generals very often get it wrong, but often too, they know what they're talking about, and at the very least, no one can accuse McCaffrey of cheerleadering for this administration.