The world faces a low-fertility future that will 'completely reconfigure' the global economy

• 97% of countries will fall below replacement level fertility rates by the end of the century, according to a new study.
• Shrinking fertility rates pose economic challenges of workforces shrinking and aging populations.
• Elon Musk has voiced concern about what he regards as impending "population collapse."

By 2100, over 97% of countries will have fertility rates below the replacement level, a Lancet study forecasts.