Flee from what? a war with aliens? Natural catastrophies? Localized conflicts? Or are you talking about political refugees? A world is essentially impossible t

Flee from what? a war with aliens? Natural catastrophies? Localized conflicts? Or are you talking about political refugees? A world is essentially impossible to achieve anyway, because super powers don't want anyone to dictate rules. The EU is not a mini-world government. it's an attempt at unifying many small nations to achieve peace and World power status. on their own, European countries are at the mercy if the US and China.