But is the burden due to ever increasing age, or rather due to ratio of young to old? I think I am asking that if the ratio caps out at 1:1 (or if I understood

But is the burden due to ever increasing age, or rather due to ratio of young to old? I think I am asking that if the ratio caps out at 1:1 (or if I understood Hans Rosling, there will eventually be equal sized aged cohorts (same number of young, middle aged and old people), is that ratio sustainable? Can we actually have the 20-60 aged people support the 0-20 and 60-80 cohorts? Sadly it seems we won't have to deal with immortality for a while yet!