They're assuming an exchange rate of 6.16 RMB per dollar in 2028. If the US continues to grow mostly by inflation with very little growth in real terms, then the dollar should depreciate. If the currency doesn't adjust, then the RMB will be even more highly undervalued given its purchasing power. That doesn't seem very likely. And even if the exchange rate prediction implicit in IMF estimates comes true, then the US will end up with a highly overvalued currency, which is just going to kill domestic manufacturing and make them more import dependentThe IMF has released the of its World Economic Outlook publication, which extends the horizon of its economic projections to 2028.
In 2028, the IMF projects China's GDP to be $27.49tn against USA projected GDP of $32.35tn. That is to say, the projection is for China's GDP in 2028 to be 85% of USA's GDP, up from 71% in 2022.
This is a significant downgrade from the October 2022 projection (93% in 2027), which was in turn a slight downgrade from the April 2022 projection (94% in 2027).