I suspect we can find a place for them outside of our most densely populated urban cores. The popularity of cars isn't in itself a scandal. The scandal is that cars still enjoy undue priority in places like Midtown Manhattan, it's that urban neighborhoods were destroyed and divided by interstate highways, it's that most cities no longer function properly for the carless.
I think the world outside USA would want a word with you about that "most cities" part.
That seems unconstitutional and a bit like North Korea where they restrict cars to specific areas and ban it in others.
There is no Constitutional right to bear cars.
In my part of the rural US, one can get an isolated hour of horseback riding for $20 or so, or maintain a personal horse for a few hundred a month (if kept at a stable run as a business for that purpose; cheaper if you have your own property suitable for housing the horse).
I can see car garages and designated driving areas becoming the riding stables of the future.
What about people who genuinely love to drive cars & ride motorcycles? Are we a danger this utopian self automated future? I just don't see it happening. There's so many people that are enamored with cars and motorcycles, who love the sensation, independence and freedom derived from the experience. Older manual Ferraris or air-cooled Porsches appreciate in value for a reason.
I almost lament at the future where an entire generation will grow up without experiencing such "archaic, manual and dangerous vehicles" because it will be too expensive, much as classic supercars will remain out of reach for majority of the population.