Was there any chance of Bangladesh reuniting with India after it achieved independence from "West Pakistan" in 1971? I really don't know if anyone proposed it at the time. Maybe the war goes a little longer and the infrastructure/human capital/intelligentsia are more heavily damaged?
This would really screw up Pakistan going forward, by the way, since the whole point of Pakistan was that Muslim Indians couldn't get a fair deal from the rest of India under majority rule and they need their own country. If a huge Muslim population joins India, the main purpose is invalid.