He said he expects the US to remain a dominant economy but that the world of 2050 could look very different.

"The United States is likely to retain a strong global influence, even if it does not have a podium place in the top three. By 2050, the three largest economies in the world could be China, India and Brazil and after the United States, the fifth spot might be taken by Nigeria, as bizarre as that might sound now."

Miranda Carr, head of China research at London-based investment research firm NSBO, is more conservative than Hu, predicting China will become the biggest economy between 2025 and 2030 and double the size of the US by 2050.

"In some sense, it is entirely plausible that China could become twice as big as the US by 2030," she said. "There is phenomenal room for growth in China, space for major industrial development, and once China gets its own world-class companies, they have a huge domestic market as well as an international market to serve."

She points out, however, that for China to make such progress, it will have to achieve near double-digit growth for a continuous period of nearly 40 years, which would be almost unprecedented in economic history.

"There are really few examples of that. You would expect some hiccups along the way."

George Magnus was one who forecast such a hiccup in his book Uprising: Will Emerging Markets Shape or Shake the World Economy? published two years ago.

He anticipated a so-called "Minsky moment", a phenomena named after the US economist Hyman Minsky who warned economies faced an investment bust if they became over-leveraged.