I agree that it could work. I'm not sure I'd want that because I expect that it would make those roads very hostile to pedestrians since you'd probably want to

I agree that it could work. I'm not sure I'd want that because I expect that it would make those roads very hostile to pedestrians since you'd probably want to forbid them from crossing outside of designated areas and only when authorized. You'll probably need some dividing walls between the street and the sidewalk. In many countries it would be a huge culture shift, and IMO a step in the wrong direction. We don't need more urban real-estate devoted to cars.