[pfdietz]

A mandate would be only one way to reach that state, and I don't think it would be a good way. Better would be a situation where female children become desired over male children, for example because they have better career prospects. In a female dominated society, discrimination against men could be a thing. Today, already, female students on average outperform male students in school and university.

[justonenote]

my comment was tounge-in-cheek, pointing out that its essentially eugenics which is a controversial topic. although apparently less so when its applied to "Y chromosome holders" as you can see in a sibling reply where this particular group of people are deemed problematic and something that should be got rid of.

[pfdietz]

In a mostly-female world where women reproduce by artificial insemination I could see the sperm being marketed with focus on the qualities of the source. This is positive eugenics, albeit being driven by individual decisions, and could include genetic screening. Indeed, selection by women of desirable mates is already a kind of eugenics.