Do you think capitalism will become obsolete once the human population is to large for earth to support?

How would capitalism work in a society where there isn't enough room for any cities or development? If the government were to restrict the amount of children one may have how would this not inevitably be the fall of capitalism? If people can know longer buy own islands or own a house with a backyard or drive and own a car because the roads are to congested with commercial and public transit vehicles how would capitalism and free trade not become impossible? What good would money be if it can't buy anything because there's nothing to buy?