The Limit of Possible Population in the World

Having the largest population in the world in one of the most polluted countries doesn't seem like the best option for the planet. "Population essentially has long been the pair of elephants quietly humping in the corner of the room" The Japanese Prime Minister this week addressing Japan's falling birth rate says that if Japan is to be able to continue to function as a society it was quote now or never to address its low birth rate. 28% of Japan's population is over 65 so are we now heading towards a world where essentially half of the global population are extremely old and the other half are looking after extremely old people? I'm just trying to work out for a good person guys yeah no you're