If countries want to solve their fertility problem, they can waste their time with various tricks and "incentives" to postpone what they'll eventually have to do for geopolitical reasons alone, which is to go to war with their own business community.
Capital controls, tarrifs, sector bargaining -- the exploding heads of think tank libertarians guide the way like lit torches through a swampy marsh.
If wage earners can be assured that they are taken care of irrespective of the spasms of the global market, they can have children. Otherwise they will persist in their state of soft rebellion, which is marked by low fertility and low laber market participation, among others.