Japan, with its decreasing population, is leading the way with this (whether you wish to call it "degrowth", or something else).
I see this as a GOOD thing, although all of you do not.
A Japan with 50% of the population it has today WILL STILL BE "JAPAN" -- so long as the Japanese maintain their strict policies re immigration and "who is to be considered Japanese".
Western Europe, on the other hand, is headed in exactly the opposite direction. They, too, have declining birth rates, but have chosen to import "migrants" who bear no relation to them, ethnically, religiously, culturally, or otherwise.
The result will be the inevitable extinction of the whites of Europe.
They'll go to their fate as did the Hemingway character describing his fall into bankruptcy:
"Gradually, at first. Then... suddenly".