/Very cool post, I had not heard of this. Makes me miss NYC a little.
It stands to reason that as building technology continues to improve, we would be able to create larger and larger structure. This will continue amplify the vertical-only problem, and it makes sense we'd have a solution like this.
Although, I'd still vote for the tubes from Futurama.
Haha agreed I'd second that vote on the tubes. Manhattan would end up looking like a giant hamster cage.