I do have to say a Greater Pakistan sounds intriguing. It'd certainly be a boon for the Afghan portion as they now have access to ports. Whilst those territories in the Hindu Kush might be very important as that is the spine of the country.
The problem of East Pakistan still remains though, unless it is decided in this whole process to relocate... Bangladesh.
I reckon without any changes Bangladesh would still become its own country - but Pakistan may well have more Iranian concerns, since they now share a much longer border with them. Plus, Russia is a bordering trade partner.
Hmm, interesting - I imagine that the long-run effect would be more Federal Provinces? in Pakistan for the Afghans.