As the article points out, US has been below replacement birthrate(2.1 children per woman) since 1971. Immigration is the only reason the US has continued to have a growing population since that time.
1.6 is bad but many industrial countries have the same issue–only they don’t have strong immigration draw(or don’t allow it) to fall back on. East Asia (Japan, South Korea and now China), as well as southern European countries (Portugal, Spain, Italy) have had crushingly low birth rates for years.
Social programs, entitlements and politics are incredibly affected.
At the end of the day, people are being worked so much and are so stressed they can’t enjoy or don’t want to entertain bringing a new life into what for many countries is a vicious cycle of exploitation.