And unless the Earths population becomes so large that every square inch of the planet is as dense as a place like Kowloon, cars will continue to fill a use that bicycles and public transport can never fill.

Cars didn't exist until 200 years ago and didn't gain the depandance they have now until 60ish year ago. Cars will cease to exist sometime in the future.

We're living in a small bubble in history where cars exist, the question is if we want to gradually reduce dependancy on cars now, or wait for the forceful bandage removal.

but that would require major reworking of large areas.

Yes, that's precisely what will be required. There's no getting through this without implementing massive changes to our way of life. Everyone wants there to be some kind of easy get-out-of-jail-free card, but that's not how it's going to be.