But reality shows it is happening, it is accelerating, and young people are part of the problem.
It's a real thing, and the consensus seems to be it's irreversible, however bizarre it may seem to us.
Will it disappear as we know it? Yes. But that is true everywhere. The America as you knew it in 2010 is also gone forever (and not for the better, unfortunately with its current politics). Same in Europe where the nazis are trying to take over. Change is a constant.
The South Korean population time bomb is a completely different thing to America in the 2010 changing.
Have you read what people who study demographics currently believe about South Korea. An informed opinion is really needed to discuss this, this is not about "feelings".
Doesn’t the fact that the people in said culture have decided it’s no longer worth reproducing, en masse, because of how their life is, imply that a lot of people wouldn’t actually like that kind of thing?
But it's going to cease to exist as it is anyway. One way or another. And the people that remain will not be staring at a wall waiting for it to end. Also, young people seem to have a radically different mindset there, which is what tends to happen when they see their parents screwing everything up.
Maybe the culture isn't there yet but it will be. Having said that, I would never be happy to live in a country with strict moral codes like Japan or South Korea. But I'm sure many people would be. In particular conservatives tend to love these societies, you often hear comments like "this is what we should do here in the US".
I'm a raging pro-lgbt polyamorous kinky progressive so for me it would be the wrong place. But there are lots of people that would love this kind of thing.