One thing Tokyo does on smaller streets is have no sidewalk at all, but people can just walk in the middle of the street.

Because there's so much foot traffic on these streets, the only reason you'd drive down them is if you really need to

I don't think this works as well in planned cities like NY without getting rid of all the one way roads to offer alternative paths

I noticed this behaviour in the smaller streets of Hong Kong as well. Makes a ton of sense to me.

I would imagine the advent of delivery drones would be a nice solution to getting supplies in and out of dense urban areas, after which there would be no need for allowing vehicles (other than emergency or public transportation).

The biggest delivery truck traffic is for furniture, goods (one or two UPS trucks for an entire building), or garbage. No amount of drone tech can reduce/eliminate truck traffic for an entire building.

The slightly more sane idea would be to look in the other direction, and build underground. That would be extremely expensive and have to deal with all sorts of issues, but at least it's physically possible.

The actually realistic solution is to focus on developing housing and infrastructure in the outer boroughs; Brooklyn and Queens are full of the absolute worst kind of inefficient quasi-suburban accumulated sprawl.

Or build the street up 1 level and have an underground level on the current street - isn't this basically how Chicago built sewers?

close. at chicago, they also lifted the buildings 1 floor up. if you don't do that, building owners will be mad at the loss of their first floor.

Yeah good luck getting a drone to deliver a 400pound pallet of soda.