Just a few days ago, I heard that India’s population will overtake that of China by the end of next year. Why? China has used harsh policies restricting the size of families, while India hasn’t. Therefore I predict that the period where China is the world’s leading nation will be short — a couple of decades at the most.
The liberal free-market theory of international economics is based on the comparative advantages of nations as the determining factor in where economic activities of various types will flourish.
It turned out that China's comparative advantage was an intelligent, educated, competent, disciplined labor and managerial class.
India has a large population, but their IQs are considerably less, the education is very uneven, and the multiplicity of languages is a problem for social and political cohesion. Plus there is religious conflict, since they have not suppressed religions nor removed caste differences.
Therefore, it is unlikely that India will become competitive with China.