This is a very long term issue, but as government is increasingly tempted to crack down on the fun side of motoring there will be less incentive to own a car.
Firstly, speed cameras are making it harder to enjoy driving quickly, as does increasing congestion. Within ten years, you should expect that engine speed will be electronically limited as you enter speed-restricted zones. The justification will be safety and climate change, and it seems inevitable that government will enforce such a move.
Secondly, there will eventually be a move towards electronically driven cars on electronic highways, caused by the need to tackle congestion by taking driving out of the hands of people with poor driving skill, who cause most of it.
With these pressures, the personal emotional attachment of a driver to a car will reduce greatly. With all the ego and emotion taken away from car ownership, there will be much less need to buy a car, and much more susceptibility to fleet ownership.
In fact, fleet managed, electronically driven cars would be an ideal substtute for public transport, increasing social inclusivity, greatly helping the environment, reducing congestion and helping the economy. Win win win!
So, private car sales might well fall, with far less choice and variety of cars, simply because there will be far less personal involvement with cars. Good news for fleet managers in the 10 year plus time frame.