Joe Afghan doesn't have strategic goals, he wants to live his life in relative peace. Joe Afghan Warlord really is in much the same position as they have been since the arrival of the firearm; they have warbands based on a fluid and changing mixture of religious, linguistic and ancestral ties.
The Taliban does not exist in the way that the US government exists. There is no continuing organisation with a command infrastructure, the US and its allies are fighting the Pushtun culture.
Your first paragraph above, I conceded before you wrote it
"As both the Soviets and the Americans show this probably isn't possible for demotic states. Imperial commitments aren't popular."
Will the Taliban bankrupt us by forcing us to spend all our money on UAVs? Maybe not, but they can still make making war on them prohibitively expensive.
I have studied military history for less than sixty hours total. I feel confident in saying that the Afghan war is unwinnable as it is, and will continue to be waged, for the same reasons Vietnam was unwinnable. The US will never win a war against guerillas, ever, because the tried-and-true strategies that work are illegal under US law, and far more importantly, repulsive to the US populace. Oh, and because the US's only existential war was with itself. That a country with an ocean to the sides and mostly deserts to the top and bottom has the world's biggest military is ridiculous.
Seriously though. How to Win the War in Iraq
Any time your convoys are so much as fired upon bomb the nearest population centre into a smoking crater. This'll even work if you evacuate everyone in said population centre before you destroy it. This way, you don't have to do intelligence work to figure out who did whatever it was that pissed you off. Everybody nearby has an incentive to dissuade, lethally if necessary, the local hotheads.
Collective punishment, it works.