There are lots of other things where people say “there are millions of us let’s do x together” where nothing happens. As example, plenty of people likes old cars and wish that car companies will build cars like in the past and nothing happens.

I think it would be easier for existing cities to prioritize public transport in new areas that are being built in the city. It would be a smaller step, people can move there and still keep their job.

There are many other factors than public transport that attract/attach people to a city or town. Like friends, families and jobs. And it takes a long time to build a city from nothing and even longer to rebuild an existing city. I don’t think it will be as smooth as it sounds in your comment.