KABUL, Afghanistan — The doubts that always clouded the NATO mission here have assumed a grim finality for many Afghans now that the end is in sight. Time is running out for the key issues to be resolved, they say, and they fear the conflict will escalate for them long after it ends for America. And so all the interested parties — politicians, civilians and insurgents — are now maneuvering themselves into position for a post-US future.