rickair7777

Yes, IF the developing world can become sufficiently developed then experience has shown that fertility rate will drop (not accounting for possible religious or political drivers to the contrary).

But even so, there's no guarantee that will last forever and I think it probably won't. Once folks get enlightened, distanced from medieval societal values, and have bandwidth and access to all the recreational opportunities of the developed world they naturally tend to delay children, and have fewer of them in the interest of prolonging their own childhood. But take that TOO far, ie people get really comfortable with easy access to everything they need and plenty of free time they may tend to start having larger families again. Many wealthy folks have significantly more than 1.8 kids... because they can, and it's fulfilling.

Also you never know what kind of religious values might pop up in the future, I can think of one or two which promote big families and are thriving AND embracing everything the modern world has to offer. Don't assume religion fades into the background, it might not.