Writing for The Atlantic Sean McFate, himself a former mercenary, describes ideas being floated to turn the pacification of Afghanistan over to a mercenary outfit like Blackwater or DynCorp. It would report to an American viceroy, with a role not unlike that of MacArthur in post-war Japan.
McFate is apparently of two minds about this proposal, having seen some mercs do good, and others do evil. He warns against Praetorianism, although I don't see some merc leader setting himself up as a "white rajah" in Afghanistan.
The model might be a Raj-like Afghan army manned by local enlisteds with first world officers and tech specialists. Alternatively, it could be a SOF outfit of stone killers with hi-tech equipment, 'robust' rules of engagement, and no media oversight.
What worked in renaissance Italy might work in today's failed states.