Supposedly "The Iron Lady" Thatcher, feeling cocky after winning the Falklands War proposed to China the idea of the UK keeping Hong Kong in some capacity. The Chinese government responded, "We're not Argentina."
And indeed they are not. The slow travel of national power may well have travelled from China to Indie to Persia, to Europe to The US and back again.
On the other hand, since WWII, many nations have been predicted to surpass the US and failed. The next couple of decades will be interesting. When the Orange Menace is off the world stage, the US may get back on sound footing.
;)