The more we have immigrants stocking supermarket shelves and constructing infrastructure the more we can focus our high end R&D on things like biotech, medicine, space, and the like. That’s economics; comparative advantage is real.
If Japan can automate many of these things they will end up being leagues ahead of those who solved it with immigration and will end up selling the solutions to the rest of the world.
Countries relying on immigration are going to get strangled and fall behind those that found ways to continue to develop themselves.
I wanted to double check so I googled it and found this, looks like there’s new visas for things like construction: https://www.mofa.go.jp/files/000459527.pdf
That is true for every country on the planet.
One of my friends born there did his undergrad and masters in aerospace engineering in the US as there's a lot more programs and jobs here. When he went back due to family obligations he discovered he wouldn't be able to get a job beyond translating manuals. He's been told over and over again that if he had to leave Japan for school then clearly something must be wrong with him. So besides the undercurrent of racism, similar problems are found by native born citizens that don't conform to these expectations.
China alone could absorb all that workforce and still have room for more given that their fertility rate has been below replacement for close to 30 years now.
It will be very interesting to see how that affects both China and the world...