Before answering, it is important to distinguish what kind of cities we are talking about. North American cities, which to date have bet a lot for the car and the suburbs. European cities, which have been oriented more towards densification and public transport. Or giant cities, and some new ones in Asia, which are sometimes built almost overnight, and contain more than 10 million inhabitants.
For the purpose of this response, I will focus on European cities. My vision for these cities within this century is that they will evolve in three basic axes of transformation: self-sufficiency in resources, transportation and collaboration.
They will be self-sufficient but interconnected cities. In the future, European cities will take the global leadership in becoming more self-sufficient in terms of water, renewable energy and urban food. However, they will share with other cities in the same country, region or the rest of the world all kinds of innovative trends that improve the efficiency of their management.