i think it's possible. but there isn't a government (with its current laws) that exists right now that i think would stand through that. i think it would be better if there wasn't just one cheif executive, that person would have too much power. and there would have to be representatives from every region. the laws would have to be very lenient. but i do believe if everyone spoke the same language it would be highly likely. i mean... the u.s. is a pretty big country, and unless it's taken over i don't believe it will ever crumble because of the people within the country. i believe it could be like that everywhere, like i said. if laws were more lenient. at certain times in history there were people who ruled over almost all the world. the countries that are here right now would have nearly the same authority just like states within the u.s. have separate authority from the central government.
it seems like with a central government the only laws which they could really have authority over would be basic moral laws (murder, war, rape, robbery) and it would keep economic stability.