Everyone knows Japan’s demographic woes.

Already the oldest, “grayest” nation on the planet, the nation’s population will plummet as fertility rates remain well below replacement. This will pose potentially overwhelming economic and social challenges.

The dirty little secret is that those problems can’t be fixed. There are “solutions” — immigration, labor market reforms that grow the workforce, robots, social services that inspire women to have children and creating economic opportunity so that young men want to start families — but they won’t be implemented in time or in scale to do the job.