A few comments on the declining population discussion.

Investment: Japanese companies invest too much, and have been doing so since the 1970s. Returns on private investment are well below those in the US and other rich countries. Over the past 30 years, Japanese companies invested about 4 percentage points more of their output than did American companies (17% versus 13%).

This over-investment has several consequences:
insufficient employment of labor, lower productivity, lower personal income because corporate profits are not given back to shareholders in the form of dividends but used unproductively by the firms. I attribute over-investment to weak corporate governance (that is, insufficient attention to shareholders). I am willing to entertain alternative explanations.

Fertility: There is evidence that the fertility uptick among the richest countries is an effect of greater opportunities for women in the work force, greater participation of men in household activities, and better child care facilities. However, the uptick is not very large. See: James Feyrer, Bruce Sacerdote, and Ariel Dora Stern, "Will the Stork Return to Europe and Japan? Understanding Fertility within Developed Nations," Journal of Economic Perspectives (Vol 22, No.
3) Summer 2008: 3-22.
Myrskyla, Kohler, and Billari, "Advances in development reverse fertility declines," Nature, 6 August 2009, pp. 741-3.

A warning here: a friend who is a leading economic demographer says that all such findings are a bit flakey.

Ageing: Look at actual participation rates, not simple age ratios, to forecast the labor force. The decline in working people does not look nearly as scary as it does with simple age ratios. Moreover, more vigorous demand for labor would push up participation. And, don't forget the women.

More on ageing: The evidence suggests that ageing is associated with delayed senescence, rather than extended senescence. The implication is that today's 70-year old is as healthy as yesterday's 50-year old.
Health care costs are rising for everyone, not just older people. The extra costs associated with the older population come from their existence, not their age.

Finally, is declining population and slower growth a problem rather than a description of a situation?

Arthur Alexander