yes, that might actually be _the_ biggest incoming issue china has (through much much less because of housing prices).
Basically by combining one child politics with various cultural and economic effects lead to a very strongly favor for having a boy over a girl. Combine that with natural reduction in birthrate due to reduction of poverty and some other factors it lead to a situation where China isn't just approaching a shrinking of population size but more like a collapse which could easily lead to various social and economic emergencies (like collapse of rent system, collapse of health system, problems to feed all elderly people etc.). Given the current "moral" direction of their government I wouldn't be surprised that if they don't find a better solution they might either start a war to kill many of their young and mid aged single men and/or start to mass euthanizing old people, at least if sick and/or poor. They even have the perfect excuse wrt. of they PR represent that: "hey we just copied Canada why are you complaining".