The conventional wisdom is that Malthus has been proven wrong and that population growth is slowing anyway.
The problem however is that humans have an infinite ability to reproduce, and most major religions encourage this. Only the Chinese have the wisdom to see the problem of runaway popuation growth and they have put a kibosh on it. The United States, dominated by Christians and whiny liberals, will never take the hard measures needed to curb runaway population growth. Not now, and probably not in a hundred years. (But who can see the future with 100% certainty?)
Although population growth appears to be slowing, or even going the other way (declining population) in many modern country, but the problem is that every woman doesn’t have exactly 2.1, or 1.8, or 1.5 children. A birthrate of 2.0 often means that one woman has no children at all while another woman has four. This means that the genes which cause fecundity will be much more prominent in future generations. I also suspect that genes correlated with fecundity are also correlated with other bad characteristics like low future-time orientation and low IQ, or the tendency to superstitiously cling to religions which encourage extreme childbearing like ultra-Orthodox Judaism. While much is made of high Jewish IQ, it is almost always secular Jews who have the high IQs and not the extreme ultra-Orthodox who tend to be rather prole. Even in Israel, they are starting to see the ultra-Orthodox as leeches who don’t contribute to the economy and don’t serve in the military.
So in the future, we will see increased fecundity of people with undesirable traits, while the upper classes continue to have few children because it takes so many resources to give children the human capital they need to remain upper class.
The next question is, what about genetic engineering? Well, for starters, it’s a science fiction technology, so who knows when, or if, that will ever be available? But when it does start to become something that can be used on humans, it will be the Chinese and not Americans who develop it first, because the Chinese don’t have all those Christian religious and bleeding-heart liberal attitudes to stop them. The Chinese will be using genetic engineering to create an obedient slave race of ape-human hybrids while we are still debating stem cell research. If such a thing is possible, of course. Or maybe, with robots, there won’t be a need for an obedient slave race, so that won’t happen.
I never see the U.S. or other Western governments mandating the use of genetic engineering because it sounds too much like Hitler, so if it’s legal, it will be used by people who have a lot of future-time orientation and want to have better offspring. In other words, the upper classes will use it to improve their own children, and the lower classes, where women already just give birth out-of-wedlock to the spawn of drug dealers and the like are not going to invest in genetic engineering.