No kids = no Japan in 100 years.
Even in one of the most overpopulated countries in the world people say shit like that. It's fucking unbelievable. You're talking about millions and millions of people all suddenly deciding not to have children even though it's never happened ever in the entire history of mankind. What the fuck else are you going to consider as a possibility? Maybe the sun will turn blue. Maybe the salt in the ocean will turn to sugar. Maybe gravity will reverse itself. Maybe ants will develop super intelligence and enslave mankind. Maybe all our fingers will fall of for no reason. Or maybe everyone will just suddenly quit fucking.