Now, here's a good article from the Christian Science Monitor on what the plan will most likely entail. It'll have several points, which I'll take in turn.
Plan: More troops, to engage in combat missions and train the Afghan forces.
Possible problems: It costs tens of billions of dollars a year. Troop deaths will spike. The Taliban only have about 10,000 fighters anyway, so what makes them tick is that they've united the Pashtuns who feel largely left out of the new government. Throwing more forces at an occupation already 8 years old and counting is probably not going to win a lot of hearts and minds.
Plan: More civilians.
Possible Problems: According to CSM, there won't be enough of them because we're short on civilian experts for this sort of thing. Second, how do you go about building infrastructure in the second-most-corrupt country on Earth?
Plan: More Afghan National Security Forces.
Possible Problems: 400,000 security forces? How do we stop them from being clan-aligned? (We can't.) If we're training Hazara security forces to patrol Taliban regions, as we've done in the past, this is pretty much guaranteed to backfire. Since Afghanistan is so corrupt, who's to say that these guys won't exploit their position, as security forces nearly always do in lawless regions? And really, 400,000? That's 1.5% of Afghanistan's population. As far as standing armies go, this is getting into North Korea territory. I pity the day when the international community gets tired of paying these guys.
Plan: Deals with the Taliban.
Possible Problems: Probably the best part of this plan, though unlikely to work on ethnonationalistic grounds. For example, when the Sunnis aligned themselves with the United States in Iraq, they did so because they were being slaughtered by foreigners (AQI) in their own regions and by ruthless Shiite militias everywhere else. They fought a civil war and lost, and were facing political annihilation. (Sidenote: They still face this, which is why I don't think the surge did very much but delay the inevitable by a couple years at a huge expenditure.) The footsoldiers of the Taliban who are aligned for tribal reasons are pinched by the Northern Alliance in Afghanistan and the Punjab-controlled government in Pakistan. They would be much more likely to throw in the towel if they were facing a crushing defeat at the hands of someone who didn't give a damn about human rights or international law, like the Iraqi Shiite militias or the Sri Lankan military. To put it mildly, I'm skeptical they'll swing, but I'm glad Obama's plan at least calls for trying.
Plan: More NATO contributions.
Possible Problems: Yeah, Britain's announced it's sending 500 more troops, but they're doing so against the will of their own people.
So far the British military has lost 235 lives in Afghanistan, 98 coming this year alone. The British public is clamoring for an early withdrawal. British officials are beginning to look at exit strategies that could begin as early as next year. With the loss of support of a major ally in the War on Terror may come the necessity to send even more U.S combat forces into Afghanistan.
And mind you, this war is not exactly popular in, say, Germany either.
The problem here is that nobody really knows what to do, and the only real counter-argument to the McChrystal plan in policy circles right now is Joe Biden's airstrike-based counterterrorism argument. Targeted airstrikes do sometimes kill bad guys, but they also nearly always hit innocent civilians and pretty much never increase security. I think Biden's plan might actually be worse than McChrystal's plan.
As I've said, I don't think there is a good option in Afghanistan — that's probably why this policy review has taken so long — and with that in mind I'm for the option that doesn't cost hundreds of billions of dollars and get a lot of Americans killed before ultimately leaving us pretty much where we are now, except slightly more hated.