Why China will hit the wall ... Hard

China is speeding for the demographic wall and there is little it can do about it.

Of all the major nations, China will hit the wall the fastest.
This is the result of the "one child" policy.
China will be old and still relatively poor soon

My opinion : China will not be a strategic threat, it needs it's young men working and creating wealth, not fighting.

"China Scrambles for Stability as Its Workers Age - New York Times:
"The proportion of people 60 and older is growing faster in China than in any other major country, with the number of retirees set to double between 2005 and 2015, when it is expected to reach 200 million. By mid- century, according to United Nations projections, roughly 430 million people - about a third of the population- will be retirees."

Other key quotes:

"...the Chinese economy, which has thrived for decades on the cheap labor of hundreds of millions of young, uneducated workers from the countryside. Changes in the country’s population structure are taking place hand in hand with changes in the structure of the Chinese family. China’s one-child policy, which began in 1980, means that, beginning with the current generation of young adults, couples will face the difficult task of caring for four parents through old age.

By the same token, the ratio of workers to retired people will decline from about six to one now to about two to one by 2040."

and

"The bind that China finds itself in takes form in an often-posed question: Can the country grow rich before it grows old? Increasingly, experts here say the answer, which also has huge implications for the global economy, appears doubtful."