My current thinking goes into the direction of small private electrical golf carts for cities since those fulfill the most important requirements given to me by those who say they'd never want to give up their car. One could even make them foldable and stack them upright when parked. Slow speeds mean that not much of a safety buffer is needed in the material.
Being able to make longer trips in the same vehicle is surprisingly low on the list. It is given mainly by people with kids who want to load the vehicle in front of their house and not have to pay for several vehicles (thus having a golf cart and a normal car does not sound appealing).
Maybe someday. The problem is that there isn't really a sharp divide between dense urban core and everything else. I think about the largest city nearest to me and traffic can get pretty high speed even nearby fairly dense areas. Traffic is often jammed up but when it isn't it doesn't just move at sedate speeds.