Bro, we don't care about Afghanistan's religious affiliations. And you can't disagree to put Afghanistan and Pakistan in one bracket. They are indeed one geopolitical headache together. The Durand Line dividing Afg-Pak is not agreeable to Afghans. They even waged wars with Brits to nullify the treaty they signed after submission, only to be kicked by the British with double the force. The Pakistani stance is uti possidetis juris i.e the border between British India and Afghanistan is legal because Pak is one of the successive states of British India.
Once Pak dissolves, the Durand is erased and borders will go back to pre-Durand postions. And before Afghans can take a chunk of the remnants, a deal can be made to grab our pie in the North. Heck, we can even keep some border territory of Chitral (Yarkhun tehsil or union council whatever they call it) in exchange for erstwhile NFWP to Afg. The Indian border with Afg will become more than 107kms.