The IMF has a relatively smooth forecast for nominal GDP growth out to 2022 for all countries.
The forecast China to close the gap from $7 trillion less than the USA in nominal GDP in 2020 to $6 trillion less than the USA in nominal GDP in 2022. They have a slightly accelerating trend to the gains in GDP for China.
Extrapolating the IMF forecast would indicate that China would pass the USA in nominal GDP in 2030 to 2032.
In 2015, IHS forecast that China would pass the USA nominal GDP in 2024.

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