To preface this comment, I'm looking at the Afghanistan situation from an American POV:
Whenever I hear about how we are going to resolve the situation in Afghanistan the solutions always end up being:
(a) Leave and let Afghanistan capitulate to the Taliban, returning it to a pre-2001 state.
(b) Stay there indefinitely, while maybe recruiting more allies, to prop up a weak Afghan government (just kicking the can further down the street).
or
(c) Make "peace" with the Taliban and allow them to participate as a legitimate political party (which is really just option (a) but with face saving for the US)
There have to be other solutions to consider.
I know there is a stigma with Erik Prince and Blackwater, but is the idea of an "Afghanistan Company" really that bad when compared to what we have now? I'm not saying to mimic the East India Company when it comes to colonization, but a private organization that manages private efforts to solve the issue. Privatize the war, incentivize mining & refining industries to fund the deployment of a mercenary army in exchange for lucrative contracts in Afghanistan's rich mineral deposits. There will have to be checks and balances on this private army, and it will have to train and coordinate with the Afghan National Army. There will have to be an international body providing oversight and strict penalties for violations.
This plan, theoretically, should generate a more robust economy that employs tens of thousands of Afghans, bringing in funds for the Afghan government to build infrastructure, schools, electricity, etc. Hopefully the employment/poverty reduction and new business opportunities that will arise out of the stronger economy will dissuade local Afghans from taking up arms. If violent elements remain, there is a private army with the Afghan Army to meet them. Regardless, it will turn Afghanistan from a lost cause into a something remotely stable. It will keep the land from becoming another terror hotbed while transforming it into something productive and will ultimately result in a more stable state.
Alternately, there might be merit in just partitioning Afghanistan into Afghanistan and Pashtunistan. Concentrating remaining coalition efforts in the newly formed Pashtun nation would be a step to save money and allow the new Afghanistan to develop and integrate with the rest of the world. Might not work out perfectly, but it might atleast localize the violence and efforts to combat that violence.