What is the most important demographic trend in the world today? Some years ago, Jimmy Rogers and I came to an easy agreement on this one; the roughly 5 to 4 ratio of young Chinese men (born since about 1980) over Chinese women of the same age. This is the result of China's one child policy, and birth screening by sex, which allows parents to selectively abort children (usually girls) of an undesired gender, so they can "try again."
Rogers and I came to different conclusions about the likely outcome. He opined, quite reasonably, that a shortage of women would lead to a rise in the status of women. This would, he argued, lead to a more peaceful China as women gained positions of power, and moderated the effects of testosterone on the ruling class. This would also sublimate the energies of the excess men. Pehaps he is grooming his (Chinese-speaking) daughters to marry into said Chinese ruling class. "Lots of luck," I say.
My vision is a lot darker. There is only one logical outlet for surplus young men of any nation; the Army (or Armed Forces). This would provide a platform for them to prove their prowess to what few women will be available. These "scarce" women will be valuable, making them very demading that their men "give them the world."
The effects will first be felt on the domestic front. More young men in the Armed Forces would give the government more options to suppressed internal dissent. The next Tian An Men incident could be a real massacre, one that made the orginal look like a "drive by shooting" by comparison.
But a surplus of young Chinese men would soon be felt in the foreign sphere. Young Chinese Army men will be tempted to "spill over" their borders in seach of young (foreign) women. Their elders won't demur, exactly. But it is interesting to note that the "China Incidents" started by the Japanese army were initated by ambitious mid-level offcicers in their thirties (the first batch of young Chinese men will be enter their thirties over the next decade.
Then we could see much of the (East Asian) history of the last fifty years relived, in the worst way. Wifeless, girlfriendless Chinese men could charge into India (as they did in 1962) because that's where the most women are. They'd probably push into Vietnam, and other parts of Indochina, as they did in 1979. North Korea (technically an ally) probably won't be off limits, and possibly not South Korea, even though a U.S. protectorate. Japan might be out of China's grasp, but not its reach.
Many say that "demography is destiny." If that's the case, we're soon going to find out in a big way.
Disclosure: Long Chinese ancestors.