Victory is simple: the elimination of the Taliban and Al-Qaeda from the country. As long as one or both of these groups have sanctuary there, we will not be safe.

The outcome you describe is desirable, but not realistic. Afghanistan is a large country with terrain that allows pockets of our adversaries to disappear.

A more practical solution is to train and equip the Afghan army well enough to allow them to fight this war with only minimal U.S. involvement.

Even this will be extremely difficult. I think the best we can hope for is a perpetual stalemate between the Afghan government (such as there is one) and the Taliban.

Incidentally, Al-Qaeda has been gone from Afghanistan for years, so the original goal of the war has already been achieved. Now we're in this for different reasons.

I agree. Perpetual stalemate is all that is attainable. When the Taliban was in power pre-9/11, they were engaged in a prolonged stalemate with the Northern Alliance, yet the Taliban was still able to maintain control of the country. I foresee something like this in the struggle between the Afghan government and the Taliban.