Scientifically proven: mingled and hybrid people are "better" people genetically speaking. Meaning the further our genes are the better. Like black white asian, mexican german etc.
I'm far more concerned about the number of people on the Earth, than the racial makeup, race, genes etc.
The "we're depleting the earth" rhetoric coming from people like Bill Gates and prince Philip, both of which have uncomfortably close ties to Nazi Germany, is auto red-flag territory.
We are not running OUT of resources, we are mismanaging them, and mismanaging the potential of other technologies and such. Everything will work itself out. Naturally.
I'm not saying you're a Nazi. I'm saying that Nazis say what you're saying therefore it warrants extra scrutiny. Also their propaganda IS race targeted so it's not an easy topic.
I'm not saying the government should suppress births. People should do it themselves. By choice. I don't see how that ultimately makes it a race/class issue.
Different cultures have different levels that they will comply with your suggestion to forgoe children. Ironically, you'll end up with a population that's less compliant and pro-baby.