What I think what will probably happen is that cities will become more compact. The suburbs will die out, and row-homes, mid-rises and high rises will become more dominant in cities all over the world. Because the compactness of the city, car-ownership and car-trips will go down (car-ownership is going down in Europe for quite some time); walking and cycling will become more widely used modes of transport. Internet shopping, conversations and 3D printing limit the use of using any transport at all. With self-driving cars, cars may become a service instead of something you own (and it will be much more efficient, since those cars will always be driving around instead of being parked, taking up space). When is this going to happen? Probably within 20 or 30 years. You may even be able to witness it yourself, Nonny. The "future" may be closer than you think Cities are here to stay. They will get more populous, but not much bigger (or even smaller!).