Even that’s not going to work. They don’t have *time* left. The nasty wake of One Child is that the number of girls born per year continued to decline and since there were lots of horny guys for each girl, a lot of the girls emigrated and left. And the CCP didn’t figure this out until far too late.
Sounds like the only thing that would work would be a “Handmaid’s Tale” scenario:
Disallow emigration of girls.
Conscript EVERY woman of breeding age to be required to have a child every two years, with grandparents helping with child care.
Party officials of demonstrated high IQ to provide stud service as needed.