Wait, is the POD before or after the Partition and its population transfer? There were around 11 million people who had to move across the border in 1947 and about a million who died in the violence. In which case the whole thing gets a bit muddled since some parts of Pakistani Punjab pre-Partition were Hindu majority and the like. A Muslim insurgency would be a bit more widespread and, seeing as there's 172 million additional Muslim in India, plus the near 200 million in Pakistan and the 160 million in Bangladesh, about 1/3 of India would be Muslim. After the population transfer, it was far more distinct, but pre-1947 India had quite a few Hindus along the Indus river (Karachi had under half a million people, of whom a bit over half were Hindu).
So a messier affair overall.
China would like a weaker India, especially considering the border disputes and competition over the Himalayan states, the Soviets might like it since no Pakistan means India itself will be concerned at the Soviet intervention in the nearby states that it now shares borders with and that means a nudge over to the US side, yeah.