There is a point when you either grow big, or you lose. Pakistan is facing threats from multiple axis, against enemies that are much bigger than her. We have India, with a massive landmass and population to the East. Afghanistan has become a constant source of enmity, terrorism and drugs. And recently we saw the face of Iran against us. The question is, is it time for Pakistan to grow bigger to face these challenges effectively?
The Afghan problem can be effectively solved, and a land route created to central asia, if the bordering Afghan territory is turned into tribaly administered territories, similar to FATA. In the coming war with Iran, Sistan-Balochistan can be taken as a buffer between the coming civil commotion and Pakistan, giving Pakistan access to oil and strategic Persian gulf location.
Taking these border lands would increase Pakistan's territory by about 25%, and give it unique access to Central Asia and the Persian Gulf. The emergent state would be stronger and be able to focus far more of its military resources against any threats from India. It would also save Pakistan from the scourge of terrorism that has bred, and will bread, in these adjacent territories.
The impending US attack on Iran would mean that the US would be happy to have a country take care of Sistan-Balochistan, reducing the difficulty the allies will face against Iran's attempts to block the Persian Gulf. Meanwhile, on the Afghanistan side, in direct clashes, the Afghan Army and administration would be decimated, which would inevitably help the Taliban potentially taking over an even more significant portion of the territories.
If we are brave enough, this could create a state that would be far more defendable and sustainable than what we have right now.
@MastanKhan