Personally as a muslim I hope & dream that not too distant in the future Afghanistan joins Pakistan federation. Its the only pragmatic way for long lasting prosperity of both PAK and AF and what would soon be roughly 250+ million muslims. For that to happen PAK policy makers need to be astute and NOT resort to knee jerk nationalistic rhetoric or ethnic chauvinism. They should Work towards some sort of federalization of Afghanistan where by it would be bifurcated into several states by ethnicity. Slowly PAK can absorb the sunni & pastun dominated states while the shia dominated states can go to iran. PAK can offer these afghan sunni states some sort of special status within their union with huge autonomy eg. China type 1 country 2 system where these AF states would have their own constitution, currency(if they want), separate judiciary, fiscal policy etc. There should be free movement of goods and people between the states & PAK and PAK will control its defence, national security & foreign policy. I think Turkey can try the same in Syria too. It would be great if weaker muslim countries aggregate with culturally similar Stronger Muslim countries thereby forming large Islamic federal states where religious identity will supersede narrow ethnic nationalism & chauvinism. I believe that's the only way Muslims can stand up to hegemony of the non-muslim world.