Mobility is the name of the game - get anywhere from anywhere as soon as possible.

With high density living we need driverless vehicles that also do double duty as elevator carriages. There is new meglev technology that will allow for more than one carriage to be in the shaft at any time and also for shafts to run horizontally through and between buildings. So perhaps the elevator door will also be your front door. The vehicles I suspect would generally belong to the system. They would drop you off and keep circulating. When you need a vehicle you simply call for one. The other big improvement we need is keeping foot and vehicle traffic totally separated.