Economics is not some magical playing field where new players enter and are handed work to be done. It is always about a competition between resources available

Economics is not some magical playing field where new players enter and are handed work to be done. It is always about a competition between resources available and labor demanded. The aging Japanese will generate demand for late life care services and that demand will stimulate supply from the youth as it becomes more and more profitable a profession to pursue. Likewise, as AI R&D becomes more and more valuable (and to whomever it is valuable to) those who would invest in it can grow their offerings until the youth start training to do the R&D. What this does not mean is that you have an absolute "shortage" of workers. It means you won't be able to get work done as cheaply if you are competing for labor resources, but it seems a bit backwards to have simultaneous discussions about the mass unemployed of America aside a conversation about how Japan has nobody to do in demand jobs. It is about how the aggregate of society values things. If the people of Japan value AI research, it will be done because the price commanded will be high for it, and will attract talent. I also do not believe for a second that advanced R&D is a discipline that skirts the bottom of labor demand where having a shrinking population might actually cost work being done, the kind of work that is barely break even and is price inelastic to growing wages. From the outset your price is above the wage floor for R&D because you don't want just anyone doing it, you want intelligent people who will already command above minimum wage. What that kind of pressure does accomplish, in a shrinking population, is more pressure on the youth you have to become educated and professional. I see it as a subconscious manifestation in the work ethic the Japanese have maintained - the US is largely giving up on mass education as an institution because the real demand for professionals in all matter of industries is not great enough to overcome the inertia of youth to have to spend the time and effort to become skilled, and it is made manifest in the student loan bubble - if there were legitimate, unmet demand for some specific profession, even computer science, the prices would keep rising until there was so much demand the opportunity presented to youth would in aggregate not go ignored, and more youth would train into that discipline. Japan is at risk of running out of the jobs that have marginal to no societal value, that require no training or expertise, and require no effort from youth. Not the ones the nation as a whole will put their money behind in calling valuable.