Source: The Importance of India
A significant factor in the power of states throughout history has been sheer numbers. … Of course, many factors other than population influence the power of states, including economic productivity and the strength of institutions. But population is a multiplier for those factors, and a country with a large enough population can exercise comparable or greater power than more developed but less populous countries.
if China succeeds in sustaining its growth trajectory economically and militarily, it will grow to overshadow the United States, wielding the same ~5x population advantage over the US that the US now enjoys over its predecessor power, the United Kingdom. This also means that the repressive and authoritarian Chinese model will increasingly prevail over the free democratic model that America has championed.
However, America is not the most populous democracy in the world. That honor belongs to India.
In a world that is quickly going from unipolar to multipolar, it is worth considering which states will wield influence in the century to come, and on behalf of which values (if any, other than self-interest!) they will wield it. If China rises to heights of power that eclipse the US completely, only India may be strong enough to speak for liberal democracy.