This would have major economic consequences, which is already the case in Japan. His message is that we have to be less selfish and think on a larger scale, in other words about the economy.
But who is actually looking at this problem in an egotistical manner and on a small scale? That would be Bernard van Praag himself! When we feel the need to have more and more children to be able to look after the elderly, this problem continues to grow, because then every generation must have more children. After all, the children of today would be elderly themselves in 60 years.
And will an ever-growing population or a constant population ultimately benefit the economy? In short, no. This may be true for Western countries in the coming decades, but ultimately, we will exhaust natural resources in this way. The earth does not have enough resources and fertile soil at present to adequately maintain the current global population. People in the third world are already feeling this effect, but we cannot continue to avoid this same fate forever.
So no, the correct message is to have fewer children! Bernard van Praag himself is the one who does not look far enough into the future and who does not look any further than the borders of Europe.