Balochistan and the peoples inhabiting its lands have always been tied into the lands that constitute Pakistan. For the river Indus was the live-blood, not just of the Balochis, but of the Sindhis, Pashtuns, Panjabi's and Gilgitis/Kashmiris. All have been tied together in various forms all throughout history because of this life giving river. One also, needs to remember, that the Indus river was navigable prior to the construction of barrages, and mass irrigation projects conducted by the British. (Alexander sailed down it to Bhambore/Karachi)
Baloch have settled the whole western part of Sindh and are an integrative part of Sindhi culture, many times now completely conversant in Sindhi only over their native Balochi. Most Sindhi chieftans are Baloch in ancestry. The same is true in large parts of Panjab.
Large tracts of South Western Panjab (Dera Ghazi Khan - A Baloch chieftan) are settled by tribes of Baloch ethnic origin. Even in Pakhtoonkwa Khyber, Dera Ismail Khan (Baloch Chieftan) is settled by Baloch tribes.
I think the geography and barren nature of Balochistan always gave it a static history, a sort of borderland. But history has shown that they were always linked to the people of the Indus, who now call themselves, Pakistani
Salam to our beloved Baloch brothers and sisters! nothing but love for you!