There is very little chance that the Afghan government will agree to post 2014 legal extra-territoriality for foreign troops in their country.
For some reason the US foreign policy establishment refuses to understand or to admit that it understands that for Muslim populations and governments it is not possible to accept the apparent superiority of the law of a non-Muslim country on their soil. This is a religious issue. Islam is a seamless garment. In Islam all aspects of life are welded together into a seamless whole. Islam is centered on law as the essence of the submision of man to God. To allow "infidel" law to be applied as being in some sense a symbol of the superiority of the infidel power is simply unacceptable to Muslims.
Iraq and Afghanistsan regretfully accepted a de facto SOFA during the wars of the last decade. They did that because they had no choice. Once Iraq developed enough leverage to refuse that concession to the US, it did so. Afghanistan will do the same.
there will be no US troops in Afghanistan after 2014. pl