Population growth will stop either by contraception or by the traditional war, disease and starvation. The rest of the first world understands but the U.S. opposes family planning. That is temporary because religious zealots do not live forever and their children are not interested in embarrassing their country just to impose doctrine.
Once population exceeds resources, the most numerous or most ruthless faction in each country kills or expels others until balance is restored. The first world can then respond by rescuing every refugee and removing any motive for source countries to control growth or it can reject them which will not bother those who expelled them. There are no good options; only bad ones that either ignore the problem or make it worse.
That is why Europe ignores but pretends to deliberate.
The biggest factor threatening that religious fanaticism may NOT decline is that so many Christonazi Taliban parents are deliberately having huge families and brainwashing them all with their rigid ideology, then getting them married off to OTHER Taliban kids as young as possible to continue the plan, which they have even given a name: the Full Quiver movement, as in “quiver of arrows” to shoot at the “enemy.”
I urge all of you to let the Discovery/Science/Learning/History Channel joint management that you CONDEMN the glamorizing of families like the Duggars, who are NOT helping make the world get better, because their sweetness and love of Jesus, however sincere, is contradicted by their intention to FORCE the Armageddon they believe in and, contrary to Christian love, actually HOPE for.