[NalNezumi]

It's considered a problem because the entire system, for most developed nations, implicitly relies on a specific demographic distribution.

Pension system in most world assumed steady supply of productive populace when it was set up. (=assumes certain young / old people ratio).

A lot of asset backed valuation (real estate etc) assumes certain consumption level, demand, and steady grow. So does inflation / investment / wealth management.

Healthcare systems (especially socialized) also have certain expectation on the distribution

If we just equally reduced population in the demographic distribution (same amount of % of men/women young/old) things wouldn't be as much of a problem.

But as it is, most countries would struggle with the transition. That's why it is a "problem" people's talk about; what is the least stressful transition strategy?

[scotty79]

Our systems need revision anyways. Nothing ever happens voluntarily. So we should be kind a glad that there is outside factor that will eventually force us to revise out systems. Because laziest approach to the problem, like letting more immigrants in didn't work out that well.