People have been talking about the "Balkanization of India" for a while now. But there are no signs of this yet. Indians have a deep rooted (albeit slightly misguided and maybe even chauvinistic) sense of patriotism.
Patriotism is there, but the main problem here is that India is pretty much already very Balkanized in geography and class if not national boundaries. It also has a strong central government. Any revolutionary/indepedence movements therefore tend to be fringe (someone in Maharashtra does not really care for farmer movement in Bengal) and easily controlled (due to the strong center). The patriotism means that any overtly violent army action is not frowned upon but rather encouraged by most who have a voice. The extreme poverty means the poor are so wretched they do not have a voice. We have met people on a two hour drive (which means only about 30 km) outside Mumbai who have never been to a big city and know nothing beyond how to get to the next day. If by some magic, most Indians become a bit educated tomorrow, and have some life other than mere existence, then we can talk about actual Balkanization. Until then, India will exist as it always has. There is also the Partition which has affected the national psyche: talk of dividing the country is like so far out there, you'd be considered a traitor a few levels before that.
that is probably the best explanation I have read yet. But it is fairly true - I really dont know why. I think religion (in its most abstract: festivities + food) has a lot to do with it. And Bollywood.
But a lot has to do with our freedom movement - the way Gandhi, Nehru and Patel unified the different kingdoms into a single freedom struggle is incredible. And that has never gone away. We actually unified India AFTER the formal independence from the British. Hyderabad's Princely State (to which I notionally belong to... and Satya Nadella ) actually wanted to be independent and was annexed by the Indian Union by force.
And now, there is so much growth and money in India, that it is really hard to make a case for Balkanization - Kashmir is an edge case with a lot of international politics. But even in the far northeast (Mizoram, etc), the struggle is for a separate federal state... only a few splinter groups demand full independence.