The new PM is sabotaging his party’s future. The hundreds of millions who speak Bengali, Telugu, etc. as their first language will not want to be treated like second class citizens.
Maybe it will be like the Metric Scare. At various times beginning in the late 60’s, many were saying “Americans MUST being using the metric system. All other developed nations already use it, so why not us too? It’s such a simple method!” There was some adaptation with liquid products, such as gasoline, being sold in Metric units, but most people still use basic units. It just never did catch on in private transaction or communication. I suspect India will come to much the same conclusion after spending x amount of millions in this experiment.