immigration will solve all these issues for now? Japan is not alone. In the future I think the babies can be born outside of the womb at some centers in volume per nation/race's needs.
Japan is remarkably uninterested in becoming an immigrant country. Guests are treated with warm, well-mannered hospitality but long-term immigrants are neither desired nor able to assimilate. How many other countries are there with a sizable population of 3rd generation foreigners?
Immigration might be a harder sell than dwindling down and disappearing altogether as a nation/culture/race/whatever else is bundled in with being "Japanese".
The fun part about the "cultural integration" aspect of immigration is that people want it both ways. In the sense, they want a certain aspect of immigrants and don't want others. Basically, they don't want multiculturalism but rather clones that resemble their society. Sure, immigrants have to take 8/10 steps for cultural integration but the host country would also need to take the remaining 2 steps. You can't have your cake and eat it too.
Immigration might be a harder sell than dwindling down and disappearing altogether as a nation/culture/race/whatever else is bundled in with being "Japanese".