Game changer? If ever a nuke is used against Indian Strike Forces anywhere, it would result in massive retaliation by India with all nuclear assets against Pakistan including counter force and counter value strikes that would cause unacceptable damage to Pakistan - Industries, nuke reactors, dams, power grids, air fields, logistics areas, troop concentrations and other vulnerable areas/points, according to India's nuclear doctrine.
So Pakistan would need to think twice before using this little toy of theirs. It was a bad idea to have produced it in the first place as the consequences for Pakistan if it is ever used will be enormous.
And, Aeronaut, what you've written is pretty well laid out just like a good military paper, but do you for a moment think that Indian war planners have not taken all this into account? Exercise Vijayee Bhava in Rajasthan is being conducted precisely for tying up the loose ends and a practice for fighting a war in a nuclear environment keeping your little tactical missiles in view.
I do not think Pakistani strategists would even think of using Nasr for fear of an immediate and massive nuclear response from India causing unacceptable destruction to Pakistan. In other words, Nasr looks good on paper but would never be used. There would be no such thing as a graduated nuclear response from India. It would be total.
Cheers!