On the eve of that historic landmark, India's first Prime Minister Jawaharlal Nehru gave a speech for the ages. India had redeemed its "tryst with destiny," he declared, "to awake to life and freedom."

Nehru's mood that day was triumphant. "The achievement we celebrate today is but a step, an opening of opportunity," he said.

Yet he was also mindful of the challenges ahead. "Freedom and power bring responsibility ... the future is not one of ease or resting, but of incessant striving."

Historians debate and judge India's past. I think it's more fruitful to look to the future. As the writer R. K. Narayan said, "India just goes on." But where to? What will the country look like in the next 70 years?

India in 2087 will not only be the world's biggest democracy, it will also overtake China to be the world's most populous country. The United Nations projects that India will have between 1.5 to 1.6 billion people seven decades from now, adding 300 million inhabitants to its 2017 population. Incredibly, those numbers will represent a decline: India would have peaked with a population of 1.65 billion in the 2050s before tapering off.

By comparison China will only have 1.1 billion people in the 2080s, having peaked at 1.45 billion in 2030. The country most likely to rival India in terms of population will be Nigeria, which is projected to swell dramatically from its current strength of 186 million to a billion inhabitants.

The world in seventy years will look more Indian and more African.

India will also look richer. According to 'The World in 2050,' a report by PriceWaterhouseCoopers, India's gross domestic product in purchasing parity terms is expected to overtake the United States by 2040. (China is already #1). India will emerge as one of the world's greatest consumers.

Strides will be made on several crucial indicators. Take illiteracy, for example. The country's 2011 census recorded 273 million citizens who were unable to read and write , representing 26% of the population. This may sound abysmal -- and it is -- but it represents a great improvement. 35% of Indians were illiterate in 2001, and 48% fell into that category in 1991.

The improvements on literacy look set to continue. Between 2003 and 2013, for example, the percentage of schools with toilets grew from 40% to 84%, while the institutions with electricity jumped from 20% to 45%. School enrollment reached 96.7%, suggesting that within a couple generations, illiteracy could finally be a thing of the past.

Or consider poverty. For all the doom and gloom that seems to envelop the world in 2017, World Bank figures show 250,000 people are lifted from extreme poverty every single day. A significant portion of this number comes from India. According to the World Bank, again, 46% of Indians were making less than $1.90 a day in 1993 . The ratio fell to 38% in 2004, and 21% by 2011. These trends are almost certain to continue.

Look at disease and healthcare. In 1960, the average life expectancy in India was just 41 years. Back then, the average American could expect to live past 67. Today, Indians can expect to live to 69, and Americans to 79. Thanks to massive improvements in hygiene, medicine, and health care, Indians are now living nearly as long as people in the West. The next 70 years will see a continuation of this trend, as access to drugs and technology continue to be globalized.

Today, only a third of Indians use the internet, compared to 90% of Americans. This too will change. Thanks to a boom in cheap smartphones and mobile data, more than a billion Indians are projected to be online by 2025, representing about 75% of the country's population. Over time, this will have transformational impacts for Indians on a range of issues from education to efficiency, commerce to communication.

But it's not all good news. While Indians in 70 years will undoubtedly be more literate, richer, healthier, and have more access to global technologies, India will also inherit some of the West's biggest headaches.

Indian policymakers have long gotten used to a 'demographic dividend' of young people. But what happens when the 600 million Indians currently under the age of 28 reach retirement age? Who will support them? This is all the more worrying given India's inability to create enough jobs.

Will the traditional Indian model of older people living with their sons and daughters continue, or will India need to build homes for the elderly? Who pays for these homes, and the attendant costs in health care and pensions? What happens to India's growth rate with fewer working age men and women, and a higher proportion of people to support?

Also on demographics, will India be able to reverse its skewed sex ratio? The early evidence suggests things will actually get worse. India currently has 943 women for every 1000 men —a product of decades of sex selection and abortions, as families vastly preferred baby boys over girls. An even more troubling statistic is that India has a child sex ratio of 919, which means only 919 baby girls for every 1000 baby boys. A skewed gender ratio is baked into India's future. It's a man-made disaster -- literally and figuratively -- that could bring anything from social breakdown to anarchy.

What about climate change? Undoubtedly, one of the dominant themes of the latter 21st century will be how a warming planet wreaks havoc on human civilization. How will India cope? What measures will New Delhi manage to put in place? India has belatedly emerged as a champion of promoting solar energy and is on track to meet its 2030 Paris Agreement commitments. Yet even those measures may not be enough. A new study in the magazine Science Advances predicts that a cocktail of heat and humidity will cause deadly heat waves in South Asia before the end of this century, potentially impacting millions.

What about communal harmony? The Pew Research Forum estimates that by 2050 India will have the largest Muslim population in the world, surpassing even Indonesia. And yet, as I write this column, India has been witnessing a clear, creeping trend of polarization between Hindus and Muslims, with scarcely believable cases of lynchings and mob violence . How will India come to terms with the reality that it is set to be the biggest home of Islam?

Then there is foreign policy. Nehru famously set a tone for India in the 1950s and 60s of being "non-aligned" with the great powers. As India has gotten more powerful, this ideology has been abandoned. In 2016, India's Prime Minister Narendra Modi didn't even bother to maintain the pretence of attending the Non-Aligned summit. Instead, India has gotten closer to the United States and Japan, and seems to be tussling with its bigger neighbor China. Will this be the new Great Game of the 21st century? If current trends continue, India in 70 years will be at its most globally influential point since the Middle Ages. What will that mean for global culture, for the struggle for resources and power?

And what of human rights? Will India keep on being a home to the Dalai Lama and Tibetan refugees? Will India speak up on regional atrocities? Indeed, will India speak up on the atrocities within in its own borders, from the skirmishes and internet shutdowns in Kashmir to the mutinous parts of its restive northeast?

More questions than answers, of course. But these are all important questions for a still-young democracy to ponder as it embarks on another seven-decade period of growth. Nehru's words remain just as valuable: "freedom and power bring responsibility."

If the first 70 years of India's freedom were about survival, the next 70 should be about putting its strengths to good use for the world at large. That would be India's real tryst with destiny.