Car ownership isn't affected. It's car usage within the city that would be banned.

There are much better transit options for dense cities like subways, light rail, bikes, and small electric shuttles. I do agree with skyways though. It would be great to have multiple levels of pedestrian and bike transit that isn't shared with heavier vehicles, and the views would be fantastic. It reminds me of the Highline: https://www.thehighline.org/about/