I think it is illusory to imagine that the USA is fighting just the Taliban and Al Qaeda in Aghanistan. There's very little left of Al Qaeda at this point, and there wasn't a lot there in the first place. As for the Taliban, they comprise part of the forces fighting the Aghan occupation all right, but what that war really is is a war between the Pashtuns and the foreign occupying forces. Most Pashtuns are not Taliban. They are not fighting to restore the Taliban, they are fighting to get foreign occupiers out of Afghanistan and restore their own control of the country. They comprise the great majority of the Afghan population.

When they succeed, as I am pretty sure they eventually will, they will then start fighting amongst themselves and with the other tribal groups (Hazaras, Tajiks, Uzbeks, Turkmen), just like they did after the Russians left. Will the Taliban win out in that fight among the different factions? Possibly. But this present war is not a war with the "good" USA on one side and the "evil" Taliban/Al Qaeda on the other. It's a war of national liberation against a foreign occupying army. So is the war in Iraq. If you wait long enough, the local people usually win such wars and the foreigners leave...(although the Tibetans have not yet been able to end the Chinese occupation, so it all depends on the relative strength, proximity, and determination of the opponents. The Chinese could exterminate the Tibetans if they chose to, and I don't doubt they are ruthless enough to do it.)