Predictions of the future are often tricky. It requires an extrapolation of a trend from today to some kind of logical conclusion, taking into account how the object changing connects to the rest of the world. There’s a real showmanship to it all, too, when you start from the logical conclusion and then explain yourself backwards.
Cities will be radically different by 2050, with zoning codes and concepts that are more flexible and the corresponding buildings will have many uses on top of each other. Suburbs, as we know them now, will require extensive rehabilitation that will work well in some places but create wastelands in others.
See how it works? This is simply the logical conclusion of a flexible workforce and a fast-paced economy with people changing careers often. Should all that come to pass, our cities will have to have more flexible structures and more agile concepts of zoning. We can easily imagine how that might look because that is what cities were like before zoning came along about 100 years ago.