What do you know about punjab. I know from first hand lots of afghanis now are claiming to be Pakistani pashtuns to get CNIC. Exemple of 2 afghani refugees. In recent crack downs they were asked to provide proof of their Pakistaniat which basically mean having CNIC. They lied and said their ancestors moved from Afghanistan in early 50's so are punjabi as anyone else, help when one speak native tongue. Hard to believe someone so old but without CNIC. One was was able to provide some bogus proof of his grand father still being alive in Afghanistan. I don't know what happened to other, was either jailed or deported. Likely released some time later.
But its tricky situation, I think maybe only refugee in camps will move back if at all. And we all know they are minorty overall among afghanis in Pakistan. Officially there are only 1 million or so refugees. Other will only move back if having CNIC become important to move around and do business. In that case those without CNIC will probably move back as well.
Another possibility I see is those who are here for decades will probably get CNIC but after certain point it will not become possible to get CNIC for anyone else. Who knows, only few thousands have gone back despite so called crack down which is blown out of proportion on PDF.