I agree with this. If you have self driving cars in particular then this is a quite likely one part of the solution.

I still fantasize about sitting in a standardised car-cabin-like box IE seats(maybe facing each other), aircon, windows, media.

And having it shuttled around like a packet on the network. Automated trains, trams, trucks, cars, drones even - all working in harmony to get you where you want to go.

That way I'd own my space. But all the moving parts can be communal and benefit from best engineering practice for efficiency at economies of scale.