Emerging markets such as India and China will eventually manage economies that are larger than the United States within a few decades, says New York University economist Nouriel Roubini.

Industrialized economies such as those in the United States, Europe and Japan are facing deflationary pressures, and emerging-market countries such as India and China are still not large enough to lead global growth.

But that will change.

“The size of the emerging markets is going to become larger and larger, and it’s going to become greater than the GDP of the United States,” says Roubini, according to Bloomberg.

“It may take 20 to 30 years, depending on relative economic growth, but the process will occur” and “we should get used to it.”

Roubini, who is credited for accurately predicting the severity of the recent financial crisis before it happened, says emerging markets are looking at a V-shaped recovery while the United States is up against a slower U-shaped economy.

Some, however, say emerging markets may have to deal with asset bubbles, especially once the United States raises its very low interest rates.

“There remains the latent risk of asset bubbles. The rapid rebound for the better in market risks after the financial crisis has led to the threat of asset bubbles in capital markets,” says Zhu Min, a vice governor of the People's Bank of China, according to Reuters.

Low rates have helped keep the dollar cheap, which has helped push other assets high.

But a rate hike could reverse that trend, says Zhu.

“What is worrisome is that once the U.S. Federal Reserve embarks on interest rate increases, this dollar arbitrage may return [to the United States], causing these bubbles to burst.”