i don't think it would be very interesting and hard to maintain because everyone would try to make things too peaceful and i feel as if we'd all be living like what the lego movie shown and go on the be too normal. first off also if there was a brony world of its own then there would probably be other like an anime world or furry world and probably some differences between different nation (and/or different worlds if you're getting it from that angle). however it wouldn't be very interesting because there wouldn't be very much new people coming in so it would be hard to come up with new ideas that others bring