What I see happening now is something good military planners try hard to avoid--- Mission Creep. It is the expansion beyond the original mission that causes inadequate and poorly selected forces to be used in ways that seriously endanger them and the mission.
What we want is the bad guys dead, and the folks that replace them well behaved. We shouldn't give a rats a$$ who runs the Afghan government so long as they behave.
Afghanistan was chosen by OBL for religious reasons as much as opportunism. It is expressly referenced in the Koran as the unstoppable army with black flags which will sweep west to Jerusalem and free it. So Aafghanistan just 'behaving' will be insufficient. It is a highly symbolic nation. It is also one that we have been given the rap of having 'abandoned' to Pakistan's ISI and the resulting internal civil wars leaving the country decimated.
Rightly or wrongly earned, that rap must be expunged and the defamatory 'stain' wiped clean. We need to install a westernized democratic pro-American 'client' state which will back up our foreign policy in the region, and help us to destabilize Iran's tyrannical theocracy, and essentially rain on the parade of the Radical Islamists from Egypt, Saudi Arabia to Indonesia. This will take the wind out of the sails of the Talibanists in Pakistan as well, and probably greatly lower tensions with India, whom we should be pursuing as a regional ally. This truly is a fabulous opportunity to defuse a really nasty explosive potential for a true 'jihad' against the West. This is a bomb which our 'friends' in Russia and China would actually love to see go off in our faces. But because the Taliban threatens them too, they are going along with us for now.
And we have to win, and then once having won...STAY. Not militarily, however. I.e., not as mission-creep peacekeepers. Send in the peace corps, and all the other sundry state-craft agencies which would allow these peoples to see first hand the truth about Americans.