Yes, US cities wouldn't be able to change to this overnight, but over the course of years and decades it's definitely possible.
It would be helpful to see real world executions.
Houten, the Dutch suburb that's really built for bikes, even by Dutch standards: https://www.citylab.com/solutions/2015/06/a-case-study-in-bi...
"Superblocks" in Barcelona: https://www.citylab.com/transportation/2018/08/inside-a-pede...
Middle class definitely live in the city in those examples (and you won't be surrounded by homeless people) . In general European city centers come from medieval times, making them very walk-able (and touristic).
There is massive gulf between what you described and carless.