I too wonder about the sustainability of the Mexico City paradigm. When land becomes precious, we re-pave and re-evaluate. In Japan (On the island of Japan), space is precious, if you are going to build it, it better last, and it better make sense to keep around. Until we reach a limit on land area, it seems that slime-mold-esque endless sprawl is somewhat inevitable. I do wish the opposite, that we would heed the lesson before driving off the proverbial cliff.