The US have the benefit of essentially limitless immigration
Except that even in the Americas the population is declining. There is a limit to it. The US can outlast many other countries because of immigration but it too has to face the same problem as everyone else.
This is quite understandable since pandas only eat a specific type of bamboo which does not grow in Finland. So had to fly it in every few days from the Netherlands. And they eat quite a lot of it. So costs mounted over time.