Some people said the BRICs — the emerging economies of Brazil, Russia, India and China — would continue to boom and shield the United States from economic troubles.

Their fast-growing economies would increase demand for commodities. American firms would sell more products to their growing middle classes, and the BRICs would send legions of tourists to Disneyland and other stateside sights. That was the thought anyway.

“Forget it,” says economics columnist and author Robert Samuelson, writing for The Washington Post.

Editor's Note: 'It’s Curtains for the US' — Hear Unapologetic Warning from Prophetic Economist.

"Just in case you didn't hear it, that was the sound of the BRIC bubble popping," he writes.

The thought did seem possible for a while, as the BRIC economies were growing fast in recent years, Samuelson notes. In 2010, China’s economy grew by 10.4 percent, India’s by 10.1 percent and Brazil’s 7.5 percent.

But their earlier high-octane figures are misleading, he points out. The countries were playing “catch-up” by improving workers' skills and adopting technologies and management practices already in use elsewhere. When the catch-up phase passes, growth slows.

It turns out that the dream of BRICs saving the United States and other developed countries was just another fashionable idea that eventually flopped. In the 1980s, Japan was expected to dominate the global economy. Then it was the Internet in the 1990s.

"These are intellectual bubbles; sooner or later, reality pricks them," Samuelson writes.

It turns out that the rise of the BRICs in the early 2000s was just another boom, fueled by easy credit from more advanced countries. The BRICs face a variety of political, cultural, and financial problems that they might not overcome, he warns.

Instead of the developing countries helping the economies of the United States and Europe, the opposite has happened, Samuelson says. The advanced nations' economic weaknesses have been transmitted to the BRICs through lower demand for their exports.

The BRICs have different problems and strengths and may perform very differently, Mark Mobius, executive chairman of Templeton Emerging Markets Group, tells CNBC.

“The BRIC concept was very clever and helped customers who buy funds a very good way to conceptualize emerging markets," Mobius says. "But when you’re investing you have to look at these individually.”

Although they've underperformed so far this year, he predicts emerging markets will now outperform the United States.

Editor's Note: 'It’s Curtains for the US' — Hear Unapologetic Warning from Prophetic Economist.