[mlindner]

The downside of "the way of Japan" is that they'll shortly have no one to pay for all the old people. Keeping old people alive is expensive.

In the US young people pay old people's social security income. You see how many people are talking about the aging baby boomers right? Imagine that but much worse.

[gumby]

Increased labor productivity through automation (and allowing people to live longer on their own through assistive devices) should ameliorate this.

There's no shortage of young people globally so Japan could always import more if they wanted to.

Again, a pyramid-based model can't go on forever.