If the Mughal empire had not declined and managed to keep it's power and maybe enlarge the empire, then there's big possibilities that two things would have happened in south Asia:
1. Making Islam the empire's official religion and forcefully implement it and make the people to follow it, thus making it the dominant religion in south Asia.
2. Making one of the Turkish languages official language, thus make the population learn it for practical uses and over time to become primary language to most of the people.