The same was said about Japan when it was on the up.

A fair point, but there are still some crucial differences:

* Japan was (and is) effectively a US military protectorate. It could follow its mercantilist strategy up to a point, but it still had to capitulate to American demands (e.g. to open up its economy + stop putting downward pressure on the yen). China has no such restrictions and does not have to open up.

* Overall the Chinese economy is far bigger and the US is far more dependent upon it than it was upon the Japanese economy in the 90s.

China still looks like it may be facing a debt-crisis the likes of which Japan had in the 90s.

China is 1 billion plus people. They have a large role to play in the world economy unless they do something really stupid or terrible. They were the largest economy in the world throughout much of history, if I recall correctly.

From the Sui (late 500's) to the mid-Qing (around 1750) most historians seem to say they were, though it's hard to say whether the Han (220bc-220ad) or the Roman Empire was "larger".

China goes up and down throughout history. Many Chinese seem to believe that China can only go up now, just like Chinese real estate prices.....

Maybe you've seen the "China 2049" adverts that popped up everywhere around China a few months ago promoting, among other things, an equal standard of living with Western countries by the 100th anniversary of the republic's founding. I guess they're designed to keep Chinese motivated to grow the economy further.