Please tell us when in the history of humanity a declining population rate has even occurred? Globally, not locally. It has not happened in recorded history.
The Black Plague in Europe? It took a century for mankind to recover economically/socially from that population collapse alone.
You don't know what you're talking about here.
If the article had posited that a great plague was the greatest threat facing mankind he might have had a better argument.
Thinking humanity will go extinct because people stop reproducing is idiotic.
Massive birth rates with a huge cadre of young people is the model of third world hell holes.
Replacement birth rates is the model of a healthy Republic.
Declining population birth rates are the model of a moribund Socialist nanny state.
Which demographic model do you think best reflects the USA, which Europe, and which Africa?
Now which demographic model do you want us to emulate again?