I've seen several timelines with Info-Pakistani conflicts like this where (West) Pakistan ends up taking Kashmir and/or Gujarat as well, but India ends up with Bangladesh. This is like the AH trope in US Civil War timelines where the CSA breaks off but the North is magically "compensated" for its losses by the author with Canadian territory. India would have no incentive to annex solidly muslim-majority Bangladesh, it would be easier to spin off as an independent state.
Would an India-Pakistan conflict have the potential to become a major great power conflict? India has traditionally been friendly with the USSR, and the Sino-Pakistani alliance is a major cornerstone of Pakistani foreign policy.
If an Indo-Soviet entente brings in a friendly government in Kabul, it could plan a joint invasion of Pakistan, followed by the country's division or partition. Bangladesh would be given independence, India would take Kashmir, and the mostly Pashtun Tribal Areas and Northwest frontier province could be given to Afghanistan. The remainder of Pakistan could be left as a demilitarized rump state, or be partitioned into republics of Punjab, Sindh, and Balochistan.
An independent Balochistan, combined with a pro-Soviet Afghan regime, could function as a South Yemen 2.0 that gives the USSR a new client state and reliable access to the Indian Ocean region.