I have some friends from India who feel the country is a bit of a British experiment, and the southeast and the northwest don't really belong with the rest of the nation. I don't know if this coughing fit of Hindu nationalism has the power to shatter the country, but the southeast is much closer to Sri Lanka, and the Northwest is its own thing -- a sort of Kurdistan for Sikhs.
Like China and Russia (and the US?), it may be so big because it has been artificially stitched together. Maybe we will see a period of fragmentation of the remainders of the imperial states, with local rule leading to more homogenous countries less prone to civil disorder.