The aging society is inevitable, what should we do?

The arrival of an aging society will inevitably lead to a significant decrease in production capacity and an increase in the idle population. If the retirement age can be raised, all elderly people can have a job, which will enrich their lives and sweep away loneliness. It also earns an income and adds a lot of production capacity to the society. Why not kill three birds with one stone in this way? Japan is such a country. I think we need to learn from this advantage of the Japanese.