>>imagine the hypothetical world with no traffic lights, because cars communicate with each other and weave through intersections.
Here is a link to a paper on handling traffic intersections. The most interesting part for me is Fig. 3 in the paper, showing capacity for different algorithms. The whole concept is familiar to those who try to time the next light, but it is nice to have some math behind it. http://senseable.mit.edu/papers/pdf/20160316_Tachet_etal_RevisitingStreet_PLOS.pdf
http://senseable.mit.edu/light-traffic/