To quote from that report "out of the 6,700 of the world's identified languages, nearly 2,500 are deemed at risk according to UNESCO, the UN's cultural body"
The chart here shows that close to 180 languages in India are either 'unsafe', 'endangered' or 'highly endangered' ..
[This chart shown here is taken from the same Economist article]
Doesn't come as a surprise as most of us hardly converse in the language/dialect our parents/previous generation use to speak. Some of us even ridicule people speaking those languages/dialect. Remember the last time when you rolled your eyes when you heard some one in Banarsi 'ka ho bhaiya paan khaiho ka' or someone from Kanpur yelling at you ‘bahuuuu mauj aarahi hai’