The other east asian nations had to switich to higher and higher sophistication of their products because their small population's GDPs quickly rose with the induction of any industry.
And hence their market was born. We had production and capital contained among only 'X' number of workers, and consequently, they made more money. They also consequently purchased more goods and paid more for them.
Consequently the real</> market, ie the people you sell to experienced an outward expansion in numbers and quality of consumers.
The real concern at this point is that China may in fact develop into some kind of a closed system where the wages are low, but all the prices of consumer goods are equivalently low. What I mean is that they may internalize their domestic market(Produce everything they consume at rock bottom prices) If thats the case then that country has the potential to bleed the entire world dry of industrial infrasture and still maintain rigorous growth due to its own domestic consumption. It means that even if we are too poor to buy their super cheap goods, the day may come, when their own people are rich enough to afford all the stuff they can make, when that day comes, they will no longer need us as consumers. I expect WWIII by then.