I was asked by the New York Times to comment on what future city transportation plans should look like. In a short piece, they could not repeat all I said, so I will expand a bit here.
My main advice to cities is that nobody, including myself, has the exact answer on how transportation will look in 2030 or beyond. (They are making plans for 2030 and even 2040 now.) Because we can't know, my advice is to design to be flexible. Design to be able to change your mind.