[Laying] low just gives us the time and peace to round up the enemy. Being quiet may be indistinguishable from losing for the average Afghan villager. There is a risk to laying low while we entrench security and governing forces and build infrastructure throughout the country. No, the enemy will fight us regardless of whether they think we might start withdrawing in a year and a half. They can't afford not to.
General McChrystal doesn't think the Taliban will do that, either:
If the Taliban simply "melt away" for the 18 months, that would provide a window for the Afghan government to demonstrate its effectiveness and turn the tide, he said.
"The insurgent cannot afford to leave the battlefield while the government of Afghanistan expands its capability, expands its legitimacy, expands its control."
We should hope our enemies are dense enought to give us 18 months of peace and quiet to hunt them down and bolster Afghanistan's security and economy.