Perhaps, instead, we can see this as a good thing and plan a graceful way back to a more sustainable population over the course of a century. Just yesterday yet another in a long line of reports talked about how humanity has not just bent but likely broken many of the Earth's ecological boundaries that humans and non-humans alike depend upon. We've known this for decades -- mountains upon mountains of studies in ecology, climate science, and many more fields. We've largely chosen to ignore it all and keep forging ahead with resource consumption and waste production.
Part of the challenge to conventional logic of what I wrote above is that the economy, in standard neoclassical economic thought, is separate from the ecosystem. The two interact, but are entirely distinct. Sometimes human society is another distinct third bubble. Instead, ecologists have long known that the ecosystem of today (and likely for the decades of concern here) contains human society which contains the human economy. So, we're better off planning a graceful descent -- one that will have less competition for resources and less harm to the global ecosystem.