Unfortunately, it turns out that if cars are significantly restricted or banned as you suggest, what actually happens is that drivers simply go to other places. Businesses in places where it's difficult to get to work find it harder to recruit staff. Shops and commercial premises that are difficult for customers to reach lose revenue. Communities that are hostile towards visitors become less popular.

I do agree with you that it would require a radical change in the funding model for public transport to successfully replace cars with a much larger-scale version of existing public transport infrastructure, but as I noted before, that would probably be prohibitively difficult politically in most places today. I think there are much more realistic alternatives, as discussed in some of my other comments here, that we could work towards over perhaps a 10-20 year time frame instead of more like 50-100.