Won't happen, first of GB will never leave Pakistan. Gilgit is very pro-Pakistan, considering they got liberated on their own and joined Pakistan, there must be a reason. Drove the Dogras and his forces out on their own and acceded with Pakistan. As a Gilgiti i can say, no way in hell will Gilgit-Baltistan ever choose to be a separate country. In fact majority wants Pakistani government to make it a province, by majority i mean the nationalist parties and the locals themselves. Same goes for AJK, majority no, much more than majority is associated with PA in GB and AJK, not kidding.
And i hope i am not wrong, but both India and Pakistan have taken out this option of independent country.
hope that answers it.