It is definitely not easy to answer this simple question with a word or sentence. Perhaps the best and only answer I could think of is that "it would make perfect sense" for the imminent future of humanity in 21st century and beyond. However within current world order we are living in today, it is far from being applicable for one 'teeny-tiny' reason - it would require canceling of what is well rooted today. The political system of Nation-State governmental polity that in one form or another exist almost everywhere on the planet. To cease that from existence is one of those Sisyphean tasks that is almost unimaginable to achieve. In simple words, in order to make City-State the only governmental polity we would have to nullify countries and to erase borders from the maps. Not only that, it also means the politics and politicians would have to reduce its influence and their numbers significantly which is also a task comparable to the impossible efforts from the mythical