The lack of economic dynamism is a consequence of demographics. When the population grows older, the society naturally shifts resources from building the future to sustaining the present. Which obviously sucks if you are part of the generation that would prefer building the future.
Everyone saw this coming decades ago. Immigration has been the only serious solution that has been proposed so far. Unfortunately many European countries are not very attractive to those immigrants who can afford to choose.
It seems quite plausible. Japan and Germany are the two oldest countries in the world, both are severely lacking economic dynamism (despite both having very large economies, built on past successes rolling forward). Both should be modern tech juggernauts, neither are.
This is an absolutely valid point, thanks for raising it. The US has (partially) addressed it by being an attractive enough economy that brings in young immigrants with "fire in the belly". These people (I am one of them), stay long enough to add economic value, and, crucially, have children who are integrated into the broader society without giving up on their native cultures.
Japan has historically restricted immigration into what was a dynamic economy, which stagnated over time.