Sadly, their mathematical assumptions are actually very reasonable and conservative. They're not saying "this exponential trend will continue", they're saying "

Sadly, their mathematical assumptions are actually very reasonable and conservative. They're not saying "this exponential trend will continue", they're saying "what happens in 30 years to South Korea if the current state continues?" And the answer is that there will be something like two 80 yr olds for every 30 yr old.