People are already doing that lmao and the general population is so apathetic that they simply don't care cheap flights and buying crap from Temu will cook us to death, they don't care that late stage capitalism has made it harder and harder for people to have families. Even if the replacement rate is magically fixed tomorrow there's still gonna be a long gap and hard times ahead.
It's still far off but I wouldn't be surprised if these were the earliest signs of societal collapse. It does seem impossible to avoid, going in cycles.
Collapse happens slowly, and then all at once. I assume humanity will eventually go through a "regression to the mean" and the collapsed birth rate is the pendulum gearing up to swing in that direction at full force.