For the significantly fewer in society who aren’t at all negatively affected by the vast majority benefiting by the elimination of car infrastructure and building of walkable cities and public transportation?

The majority of the people already live outside the mayor cities (and in my opinion even more people will leave the cities).
Having a walkable city with a good transportation system is useless for who live outside.
That Milano is walkable and have a subway train every 3 minutes is useless for me if I live outside and need 1 hour to travel the 20 km distance from where I live using a train.

Literally nothing, aside from now also having trains to the bigger cities and busses in their smaller towns.

Train to bigger cities where never the real problem, they were always present. Sometimes they have margings to be way better, but they exist.
What do not exist, and never will, is your busses in the small cities. Small cities have not a critical mass to make a public transportation viable, both inside the small town and to link nearby towns, without going to the big city of the area.