I think that there are a lot of things that go together in this issue…
We definitely do not need the sheer number of cars that exist and that continue to be produced, we won't need multiple private cars per person in many parts of the world.
But on the other hand asking people to give up freedom of movement is not likely to ever be popular, and neither should it be needed.
The solution for at least part of that is that people living in urban areas who don't regularly go out of them probably don't need to own cars, but what they do need is very good public transport to get around all of the time, and easy and fast access to a shared car system when they do want to go out of the city to places not easily served by public transport.
That's not all unthinkable, car sharing schemes exist all over the place, and they are getting bigger, better, more affordable, etc. all of the time.
The problem arises from the fact that people like to own things, and a big part of that is probably a safety factor, human history is full of wars, revolutions, company collapses, people being deceived and ripped off, and that makes many people feel more secure in actually physically owning something rather than relying on services that they do not ultimately have control over and that might 'not always be there'.
