It's not a cataclysm, but it means that for the next few generations, the fertility window of women must increase and the attractiveness of men has to increase.

It's not a cataclysm, but it means that for the next few generations, the fertility window of women must increase and the attractiveness of men has to increase. That is going to be a very slow process. There is no way this mechanism is fast enough to prevent any declines predicted until the year 2100.