The Future of Fertility

Over time there will be some subcultures which are highly fertile and if they're able to preserve that culture down the generations they will come to be much more influential in terms of sheer numbers. Are we likely to reach a point where the facility drop worldwide bottoms out and what you end up having is some cultures some fertile cultures becoming much much more dominant? I don't want a world with no cultural liberals i don't wants a world where everybody belongs to some sect  with very high walls and very little ability to communicate with each other, he says.