Like with everything there has to be a limit as to how many people the Earth can hold, and that point will come one day. If there's not enough food to go around, you're going to see the same old conflicts but at much higher scale, war, scapegoating, people fighting among each other because they have no other choice, else they will not survive. Everything will go down hill. Perhaps the government around the world will suggest to people to do like China, you can only have one or two kids. And many of people will not care and have 10.