This is a question which can be answered well enough by only one factor, time. As of now, imagining a border less world is quite a herculean task (yes, even thinking about it, is). The world sees numerous conflicts at all levels every day, among which few escalate into major conflicts that attract global attention. The European Union is indeed a a big example when it comes to the concept of a 'Border less World", but it has its own pros and cons. The biggest elements, when considering a Border Less world is trust and cooperation. Trust builds a Border less world and cooperation keeps it functioning. The interconnected borders of the European Union were challenged when the leaders of the Eastern European economies started closing down their borders on the refugees, while a lot of their Western counterparts accepted refugees in large numbers. Regardless how "borderless" the community is, there will be times when it would be tested on its cooperation. Religion, culture and race are not an issue; the greatest example for this statement being the world's heterogeneous economies. But before you even think about having a borderless world, think of the following scenarios:
1) Will Israel recognize Palestine and let the Palestinians settle in its territory?
2) Will Pakistan open its borders for a free flow of Indian nationals?
3) What about the North Korea and South Korea?
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As I have already mentioned in my answer it all depends on time. There might be a time when we all would live under an uniform International Code of Conduct. There might be a time when we make the idea of a 'Border Less World", a reality. But, that time is certainly,