The Mongol (Yuan) and Manchu creation of the artificial "China" with buffer regions and forced Hans made out of uncooked barbarians, seems it is higher on the failed state index. So let's wait and watch.
Manchus are Chinese.
There is no country called Manchuria. They speak Chinese and follow Chinese culture, there are only about 50 people in the world who are native Manchu speakers. They are Chinese, same as the majority of Mongols in the world, who live in Inner Mongolia.
Whereas India's de facto national language is English. And the people of Britain won't bother to learn any Indian language, let alone become Indians.
But if you believe Indian Hindus and Indian Muslims can live in the same country forever without any problems (especially once they start becoming a majority), then good luck to you.
I have known several Chinese of Manchu descent, there is literally no way I can distinguish them from Han. They speak only Chinese, are culturally Chinese, and only follow native Chinese religions. They have fully assimilated.
Something which you cannot achieve. Your Dharmic demographic has only shrunk against the tide of Islam, rather than you assimilating them, they have been assimilating you. Nowadays the word Indian is tied with being a Muslim, hence all your troubles in America and airports.
Muslims won't convert to Hinduism, apostasy is against their own laws. The demographic tide is irreversible for you. Though as long as you keep appeasing them with Sharia courts (you already have those) and Sharia law once their numbers are large enough, then you can hold off another partition. As long as the other Indians don't have a problem living under Islamic laws.