[somewhereoutth]

Indeed. And this burden of a top heavy population pyramid is a major reason for not having [more] kids - a vicious circle, which, if left to continue, will result in humanity simply evaporating.

A pretty depressing place, with whole towns and cities abandoned, as the dwindling population huddles closer together. Not just geography though, there would also be a retreat in the arts, sciences, etc as there are simply not enough people to maintain let alone advance these endeavours. Life would be about eking the last out of what was left over from the 'glory days', a sort of slow motion apocalypse.

[somenameforme]

I really am not following your logic here at all. You're precisely describing what happens from not having more kids.