This strategy works as long as there are more places (by volume) experiencing growth than decline. Since the trend is slower growth overall, there will be a point where global growth stops, and clearly then the strategy will start to fail.
Frankly, from a planet point of view I'd hope that point comes sooner than later.
This will play out in obvious ways (lifting retirement age etc) but ultimately the quality of life will increase overall until some sort of stable population number emerges.
Also, look at cities that have had a decreasing population, such as Detroit. They don't look so good.