All of these can implement policies to resolve this issue. The West could do so simply by encouraging immigration, though it's probably hard to gather the political will for that. China could think about such policies, but birth rate and the population pyramid are less flexible and more difficult to fake than GDP growth. Also, being an authoritarian (not totalitarian) state means that their government is not completely immune to popular demands: the one-child policy was more like a 1.5-child policy because of its huge numbers of exceptions and special considerations. I sincerely hope that they have become more careful when trying to steer population growth.