The US ain't going nowhere! At least two army divisions will remain there along with logistics support personnel and their training teams for the next several decades. Afghanistan is too important a country for the US due to its immense natural wealth and energy corridors. They will never abandon it for the Talibunnies to run riot there.
Then there are conflicts of interests to grab a piece of the Afghan pie. Iran, India, Russia, China, the US, Pakistan and the Central Asian Republics, all have their eyes firmly fixed on Afghanistan's natural resources and its energy corridor. It won't be a cake walk as the Pakistanis desire and have planned for. Their plan for 'Strategic Depth' will come a cropper. It just won't work! And to think that Pakistan has been trying to install a pliable Taliban government there since the last decade just for this purpose has resulted instead in the birth of the TTP and their attacks we're witnessing today in
Pakistan where nearly 50,000 have already been killed. All this for the mirage of 'strategic depth'!