Humans actually have hit the fertility "point of no return" quite often, but it was always geographically limited. This time, it's entire geographic regions.

Even migration won't make a difference, as it just delays the situation one generation in the new place and speeds it up accordingly, in the old place.

Doesn't mean humans will go extinct, but it does imply that we'll stop building and revert to subsistance. Humans only build when there is scarcity and progeny. 

 Time will tell. Give it a few generations to see clearly. Until then, optimism will do more to advance society than fear. IMHO.