My understanding is even as a economy if India becomes the third or second largest global GDP in 2050 AD or whenever their time comes. Only the top 10% of their population will supposedly benefit. The rich become richer and the poor and folks who live within a dollar a day expenses, might still keep struggling with creeping cost of living and other needs etc in 2050. The distribution of wealth in India is right now very poor and they will find that scenario challenging, wont become any better unless they get a dictator or have a revolution like China. The curse of being a democracy, needs collective decision making.
India, believe it or not is a socialist country at its core. Indian government indeed feeds a lot of poor people through subsidized and sometimes free commodities. A lot of people fall through the cracks in the system and YES there is a massive corruption, but a massive majority is actually served and are saved from starvation. Especially in rural parts of India
So, "living on a dollar a day" is rather a weird kind of metric in India's case because for poors, its not always the dollar they are earning that feeds them. Better metrics are direct measurement of social welfare metrics (life expectency, IMR, child stunting, access to sanitation, vaccination %age, schooling years, literacy rate etc) and consumption (number of good purchased of various kind, number of commodities purchased) as they reflect the true status of India.
They have been making a steady progress (if slowly). So yeah, in 10-20 years poors of India will still be poor in terms of dollars earned --perhaps-- but much less of them will be dying in childbirth, they will be living longer, they will be more educated, they will be less likely to suffer from childhood stunting and so on. And yes, India will be a vast ocean of poverty with small islands of prosperity. It will drag it self into upper middle income country eventually with massive difference between haves and have less.