A Private Problem?

It seems that all the problems that traditional systems of retirement face is that they are affected by long-term shifts in the population because the young pay for the old to live.  When the young form too small of a proportion of the population in relation to the old, systems of this sort simply cannot continue to exist indefinitely in free societies because at some point the young will decide that economic conditions are too harsh and they will emigrate from the country.

The money taken from the young also prevents them from investing in their own retirement accounts, which sets the stage for future financial dependence and instability.  In short, the problem with current systems of retirement is that the elderly have to rely on younger workers to pay for their retirement.  In an ideal world, individual workers would invest their earnings in a retirement account.  This account would grow over the years, to the point of being sufficient to fund retirement.
Programs like social security, while they are certainly necessary for people who are incapable of providing for themselves, are simply not viable as a means of support for retirement for the whole population.  The optimal solution for the general population to save individual retirement accounts from a young age, with social security acting in its intended role- as a safety net to guard against unexpected disaster, and not as a retirement plan.  Such a plan would be difficult to implement, however, because so many people have already come to rely on programs like social security to care for them in their old age.

Solutions to Demographic Isues

The good thing about most demographic shifts is that they will probably not have any extraordinary impact on the well-being of most Americans if the proper solutions are applied.

For the problem of the disparity in population growth between economically developed and undeveloped countries, immigration could be allowed or even promoted.  Rich countries with low birthrates and high demand for labor would benefit economically, and it would also be a humanitarian venture because the areas in which birthrates are the highest are generally places that can least afford to support more people.

Another solution to population lack or surplus would be to adjust birth rates through policies like economic incentives, subsidized fertility treatments, sex education, or free birth control.  This may, however, lead to government intrusions into people's lives, which would make such programs difficult to implement in free societies.

To solve the problem of young Chinese not being able to support their parents and grandparents, the best solution for the Chinese government would be to pursue policies that promote economic growth.  This would encourage young people to stay in the country, and it would make it more likely for expatriate students to return to their home country to support their parents.  Rising incomes would also make it easier to support the elders.  Because current economic policies have met with extraordinary success, the best policy course would be to continue what they are doing economically.  Also, another way to make the country more attractive to the young would be to shift to a freer, more democratic style of government.