China has been a strong performer among emerging economies, even if its growth has been slowing. But that's set to end, according to research firm Capital Economics.

Growth in China could plummet to 2% over the next decade - from the expected 6.0% to 6.5% target this year, predicted Capital's Chief Asia Economist Mark Williams.

"China's time as an emerging markets outperformer is ending," said Williams, at the Capital Economics annual conference in Singapore. He added that the estimated 2% growth is a "long way" from the 5% to 6% expected by the International Monetary Fund for the next decade.

Speakers at the conference pointed to a number of risks, as well as changing demographics in the world's second largest economy. That includes its debt problem, declining workforce, and increasingly weaker drivers of productivity, they said.