In the long term lowering populations means our present economic system will at some point no longer be sustainable. That's why people like Musk are freaking out about it. And its a major reason why there's such a huge push for humanoid robots to replace human labor.
Climate change is a problem and one of the main reasons why is due to our energy use. Collective human activity is pumping out more heat than the planet can sustain. This is also unsustainable long term.
If you ask me I think low birth rates are a good thing. Its better for the planet and its driving incentives to replace human labor. I'm hoping for a future in which the human population is in decline but we've replaced most human labor with A.I./robotics and due to advancements in tech and political pressure we've found a way to change our current for profit system into something sustainable and healthier.
You know on your last point, I really wish for that too, but imma be honest, I don’t think we as a global society can ever succeed as long as white people are directing everything, personally I think we gotta deglobalize and have stronger local economy, I don’t think we’ll ever have enough robots for the type of labor needed to keep our physical foundations up, also they’ll be expensive which would mean they would not help the poor people of society except for serving them fries in a drive through. Need to get back to the kind of living where you depend on most of your goods and services in your immediate and greater community. But again, these crackers are crazy as fukk and have been constantly having cold and hot wars for like hundreds of years straight at this point.