I suspect that much of the "push" by the US MIL/IND complex to stay there is simply an attempt to prove that the US can succeed where the Soviets failed (along with the opium trade etc etc).
NATO will never prevail using the present model. I can definitely agree with some of the long term, small scale alternatives that TR presented, those could prove to be workable in some capacity.
As long as NATO stays there in force and numbers, with the misplaced objective of trying to win "hearts and minds", is as long as the indigenous people will continue to fight them at any cost.
~18 year old kids with no clear idea of why they are fighting are no match for indoctrinated, religious fanatics who are defending their families, homes, land and way of life.
You better believe that the Soviets were far more prone to "taking the gloves off" than the US are and they left rather than continuing a pointless fight that they knew they could never win.