“China is the locomotive that drives the world economy” is something that’s written more than once or twice by economic journalists. I’m waiting for the first one who’s going to write that China is a whole train. Not the world’s whole train, but certainly its own whole train.
It’s already close to it now and could be — and would be — at a drop of a hat if we ever have another monetary collapse worse than the 2008 crisis and nobdy is able to intiate a new world trading currency to replace the America dollar. China isn’t anxious to be self-sustatining, not at least until it has finally caught up with the West in terms of consumer goods but, actually, it could never be fully in a condition when it might decide not to import anything at all for a very long time to come .
Until its population is a great deal lower than it is now, then China will still need to import foodstuffs, particularly if its middle class want to eat in the style of its Western counterparts. And, until the biological sciences are a great deal more advanced than they are now and metals-based products can be substituted by superior carbon-based ones, then China will still need to import crude metals such as iron ore and copper for a long time yet.
The demographic nature of China is already such that the first will be well on its way to starting in 30 years’ time. Its population will then start to decrease. From then on, if Chinese parents have any sense at all, they’ll make sure that they don’t have more then two children per family from then onwards. China’s population will then descend until it’s at a level that people feel comfortable wtih. Presumably it will be below a level when face-to-face interactions in city life are so frequent as to be stressful, and above a level which will ensure that every child is born into a welcoming local community.
The second criterion for self-sustainability is still indeterminate. It has already started with the use of carbon composites being used for airplane bodies instead of aluminium but it won’t really start getting into its stride until, say, DNA-based machine tools start spinning spider’s web-type material that is already known to be many times stronger than the finest steel, or DNA-based electronic circuits that are already calculated in theory to be many times smaller and many times more accurate. DNA as a memory device that can be read-out digitally has already been shown to last for at least 1,000 years whereas present day hard disc memories start degrading well within a few years.
In short, hundreds of years, it not thousands, will be required for the full development of carbon-based replacements for modern materials. In the meantime, however, and at any time from now onwards China could get by all by itself just as it was doing before the MIng dynasty outlawed international sea trade in the early 1400s. Today, a European industrial revolution later and a Chinese industrial revolution later, China now has within itself all the skills and technologies that the western world has, and the country is large enough for parts of it to specialise for maximium efficiency of economic manufacture and exchange and trade adequately within itself.
If absolutely necessay it would only be a matter of living with a poorer diet, and living with fewer consumer trinkets (in other words substituting other methods of ascribing or achieving social status than merely by the ownership of things).