Monogamy isn't dead as the author seems to imply by the falling marriage rates. Many people I know are not married but are in 10+ year long-term monogamous relationships (myself included). We don't ever plan to get married because I don't like the government telling me what to do and how our assets must be split in the case we decide to break up (though we never plan to). We also are vehemently anti-religious and would never support an institution like marriage for that reason either.

I personally don't want to have children because my life is fulfilling as it is and I don't want extra distractions when there is no void to fill, but I think this notion of "illegitimacy" is very outdated and should be retired.

I think a lot of the long term economic and population concerns will be solved by workplace automation and biotechnology revolutions in human lifespan respectively, so they are largely overblown. I also don't think a future child-raising industry where children are raised together in government sponsored and supervised systems would be as dystopian as depicted in Brave New World.