Now, even that is uncertain.

China has racked up a big list of big challenges that make this destiny increasingly doubtful. Increased government intervention in markets, a rapidly ageing population, mounting risks in its financial system and property market, the government's disastrous response to COVID-19, a lack of clarity on where China's long-term sustainable growth will come from - the list goes on.

We've been wrong before. The Soviet Union was predicted to become larger than America back in the 1960s. Russia's economy today is half the size of the Californian economy, let alone the rest of America.

Japan was predicted to become larger than America back in the 1990s. Japan's economy is just one-fifth the size of America's economy today, and that's on a good day.

Have we made the same mistake with our bold prediction for China?

The prediction seemed sensible 20 years ago, even 10 years ago. The rhetoric from the Chinese government was about liberalising markets, supporting innovation, expanding freedoms and collaborating with the world to boost trade, investment and friendship. It sounded great.

The data looked even better. It took just 15 years for China to double the size of its economy after it began its free market reforms in the 1980s. Then it really took off. China doubled the size of its economy again in just seven years, then again just four years later, then again just seven years after that.

If it kept this up, economists calculated that it would overtake America as the world's largest economy by the mid 2020's. But times have changed.

First, though, some maths. America's economy is about a third larger than China's, so China has a lot of ground to make up. The sheer size of the American economy and the effect of compounding means China's economy can't just grow faster than America's if it wants to surpass it, it needs to grow much faster.

If China returned to its average growth rate of the 2000s and the US stuck to its current forecasts, China would surpass America in 2025.

But this is a bold assumption. China's GDP growth rate has been nowhere near its historical rate. The International Monetary Fund expects China's economy to grow at less than half that rate for the foreseeable future - and that's assuming no major risks materialise.

A few percentage points either side make a big difference. If China and America continue to grow at their current rates, for example, China's economy won't surpass America's until well into the 2060's, if at all.

There are several reasons to think that a world-leading Chinese economy might be more dream than destiny. The Chinese government's disastrous response to COVID-19 is a case in point.

China's COVID-zero policy has been an economic catastrophe. The economy shrank in the June quarter, forcing the central bank to cut interest rates twice when the rest of the world is raising them. The long-run consequences for growth will be significant.

China's debt-laden property sector is just as worrying. Property sales fell 18 per cent in June and 29 per cent in July. New construction is down 45 per cent. People are so angry they are boycotting their mortgage repayments. Buyers have stopped payments on at least 319 projects in 93 cities.

China's long-run demographics aren't helping. Many expected birth rates to soar after China ended its one child policy in 2015. They didn't. China's fertility rate is about the same as Japan's: far below what's needed to maintain the existing population, let alone grow it.

China can't afford this. Chinese GDP per capita is less than half that of Japan, measured at purchasing power parity. China risks getting old before it gets rich.

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The Chinese government's growing interventions in its economy and in businesses make things worse. China's growth model to date has been about applying foreign technologies to a huge population and relying on demand from other countries for its exports. It's a great strategy, but it only lasts for so long.

China's future growth will need to come from productivity and innovation. Its government's interventions to maintain political control risk stifling both. China risks being trapped as a middle-income country.

If China has one thing in its favour, it's this: overtaking America is a two-horse race, and the other horse isn't looking too crash hot either.

America is riddled with social division and struggling with economic stagnation. The "Make America Great Again" movement is doing a great job at undermining the democratic and free market institutions that actually made America great in the first place.

But, for all its faults, America has one thing China doesn't: flexibility. America has an amazing ability to reinvent itself. This is thanks to the flexibility built into its political system, its legal system, its product markets, its labour markets, its financial system and its exchange rate. It's the source of the world's inventions, innovations and investments.

China has none of this. Its political system is concentrated around a single man. Its legal system has no independence. Property rights can be arbitrary. Its labour market restricts people from living where they want. Capital and investment are constrained, its exchange rate is fixed and its businesses and markets are often characterised by control, rigidity and regulation. China is fragile.

America certainly has its problems. We've bet against America many times before, including in its most difficult times, and lost. Are we making the same mistake again?