Pakistan is self sufficient in food production and other major imports are through China. Iran is next for oil imports. So yes pakistan can sustain the blow easily. The only thing is that Pakistani leaders cannot runaway in the west where their black money is stashed.
As for nuclear blackmail, it won't work. Pakistani thinking is crystal clear that in case pakistan goes down it will make sure it take India down. In case of nuclear war between Pakistan and India, Pakistan maybe no more,it will not exist but India situation will be of a man without arms and legs and teeths. That would be new India, a nuclear wasteland with people being born with defects for next 2 centuries or even more. There will still be 57 other Muslim countries but India...no more swamies.