I assume that you are being sarcastic. Since people are not inter-chageable, the large influx from outside the Continent is the single most serious aspect of the problem. Birth rates rise and fall. At the worst, the fall in the birthrate will cause a temporary crisis. But a change in the population base will permanently change the nature of the respective Societies. Europe needs a contemporary Kipling, to put the dynamics of what is going on in perspective.
No one can predict the precise point when the birthrate will surge upward, once more; but one suspects that it will, sooner rather than later. Certainly, the generation who are now children, may live to see a real incentive for having children in the inability of the State to care for the aged in the near future, causing families to look to their own families for old age security. But whatever, the birthrate will turn upward again, just as that of the American Indian did, to make fools of the pundits around a century ago, who were predicting his rapid extinction.
William Flax Return Of The Gods Web Site