Who will be among the oldest? By 2050, the majority of people in Japan, South Korea and Germany are expected to be older than 50. Some Latin American countries, which are now younger than the U.S., will likely be older than the U.S. by 2050.
The above Pew research graph, suggests that on the current trajectory in 2050 the average age in China will be 46 (up from current 35). Will that be unmanageable?
Alternately what can be done to manage the problem. First of all, now that population increase is stabilised (as it seems to be) can the birthrate be increased? I suggest that it could be increased. The first steps have already been taken by the recent relaxation of the regulations to permit some to have two children. I'd predict further relaxation in the future, and, further down the track the complete removal of all population controlling rules, with a possible exception of the ban on aborting female foetuses. From a population perspective, a stable population of around 1200 million sounds a good thing for China.
The next consideration is, can worker productivity be increased. Presently, it could be thought, too many people are engaged in agriculture, and their return is too low. Mechanisation of agriculture, at the level of the USA and Australia's examples, which is possible through more efficient broadacre farming, would permit the diversion of workers to other areas of activity, and at the same time, increase food production.
Another possible solution may be to encourage migration.
And the most important factor may be to increase productivity through the use of robots. That's also possible, already about 25% of the world's robotic machines are in China, and that can only increase
So, in the case of China, is an aging population the problem that some think it may be? I speculate that it need not be.