Why would it be???
These are two nuclear powers with powerful regional allies and enemies. Nuclear war, even if by some miracle it is kept totally regional and confined to nuclear exchange between just these two nations.
Billions die, the global food supply is destroyed basically overnight, large swathes of the globe are rendered completely uninhabitable for even single celled organisms.
India-Pakistani war has been THE major predictor for doomsday in scenarios played out through war games and tested avenues over the last decade.
Two nuclear powers going into a direct war is gambling that nobody gets desperate. None of their neighbors get squirrly, and that the entire world doesn't get dragged into the net of the two preeminent military powers of the region.
Best case scenario by conservative estimates is that a
Billion people die.
Protracted ground will will end with us all dead.