There is no question but that the populations of most European countries will decline in the next generation, and in the cases of Germany and Russia, the decline will be dramatic. In fact, the entire global population explosion is ending. In virtually all societies, from the poorest to the wealthiest, the birthrate among women has been declining. In order to maintain population stability, the birthrate must remain at 2.1 births per woman. Above that, and the population rises; below that, it falls. In the advanced industrial world, the birthrate is already substantially below 2.1. In middle-tier countries such as Mexico or Turkey, the birthrate is falling but will not reach 2.1 until between 2040 and 2050. In the poorest countries, such as Bangladesh or Bolivia, the birthrate is also falling, but it will take most of this century to reach 2.1. Even with the lifting of "one child" China has still maintained a very low birth rate. The United States also has a birthrate for white women at about 1.9, meaning that the Caucasian population is contracting, but the African-American and Hispanic populations compensate for that
The process is essentially irreversible. It is primarily a matter of urbanization. In agricultural and low-level industrial societies, children are a productive asset. Children can be put to work at the age of 6 doing agricultural work or simple workshop labor. Children become a source of income, and the more you have the better. Just as important, since there is no retirement plan other than family in such societies, a large family can more easily support parents in old age.
In a mature urban society, the economic value of children declines. In fact, children turn from instruments of production into objects of massive consumption. In urban industrial society, not only are the opportunities for employment at an early age diminished, but the educational requirements also expand dramatically. Children need to be supported much longer, sometimes into their mid-20s. Children cost a tremendous amount of money with limited return, if any, for parents. Thus, people have fewer children. Birth control merely provided the means for what was an economic necessity. For most people, a family of eight children would be a financial catastrophe. Therefore, women have two children or fewer, on average. As a result, the population contracts. Of course, there are other reasons for this decline, but urban industrialism is at the heart of it.
The contraction of the population, particularly during the transitional period before the older generations die off, will leave a relatively small number of workers supporting a very large group of retirees, particularly as life expectancy in advanced industrial countries increases. In addition, the debts incurred by the older generation would be left to the smaller, younger generation to pay off. Given this, the expectation is major economic dislocation. The most obvious solution to this problem is immigration. The problem is that Japan and most European countries have severe cultural problems integrating immigrants. The Japanese don't try, for the most part, and the Europeans who have tried — particularly with migrants from the Islamic world — have found it difficult.
The United States is an efficient manager of immigration, despite all the current controversies and past immigration scares. The American solution of relying on immigration will mean a substantial change in what has been the historical sore point in American culture: race. The United States can maintain its population only if the white population becomes a minority in the long run. The second point is that some of the historical sources of immigration to the United States, particularly Mexico, are exporting fewer immigrants. As Mexico moves up the economic scale, emigration to the United States will decline. Therefore, the third tier of countries where there is still surplus population will have to be the source for immigrants.
World population was steady until the middle of the 16th century. The rate of growth increased in about 1750 and moved up steadily until the beginning of the 20th century, when it surged. Put another way, beginning with European imperialism and culminating in the 20th century, the population has always been growing. For the past 500 years or so, the population has grown at an increasing rate. That means that throughout the history of modern industrialism and capitalism, there has always been a surplus of labor. There has also been a shortage of capital in the sense that capital was more expensive than labor by equivalent quanta, and given the constant production of more humans, supply tended to depress the price of labor.
For the first time in 500 years, this situation is reversing itself. First, fewer humans are being born, which means the labor force will contract and the price of all sorts of labor will increase. This has never happened before in the history of industrial man. In the past, the scarce essential element has been capital. But now capital, understood in its precise meaning as the means of production, will be in surplus, while labor will be at a premium. The economic plant in place now and created over the next generation will not evaporate. At most, it is underutilized, and that means a decline in the return on capital. Put in terms of the analog, money, it means that we will be entering a period where money will be cheap and labor increasingly expensive. One of the key variables mitigating the problem would be continuing advances in technology to increase productivity. We can call this automation or robotics, but growths in individual working productivity have been occurring in all productive environments from the beginning of industrialization, and the rate of growth has been intensifying. A growth in productivity so vast that it would leave labor in surplus. Of course if that happened, then we would be entering a revolutionary situation in which the relationship between labor and income would have to shift.
The pattern of falling death rates, followed by falling birth rates applies for most of the world. Saving lives doesn't lead to overpopulation - just the opposite. Creating societies where people enjoy health, prosperity and fundamental equality is the only way to a sustainable world.