Someone asked, "when will wars stop"

Assumptions:

1. History shows that Nationalism ultimately leads to war.
2. The most violent wars were fought over religious differences.
3. Dwindling natural resources will lead to war as the competition for these resources intensifies.
4. Increasing poverty and scarce food and water supplies will lead to war in the near future.
5. Nation states use force to accomplish their political objectives.
6. Nation states manipulate other states to use violence to achieve their political objectives.
7. Nation states act in their own self interest at the expense of everyone else.
8. Nation states foster division among other nation states.

How do you demilitarize earth? Should we eliminate nation states? How would you go about eliminating nationalism? Would earthlings be willing to give up national identification and become citizens of Earth? Could social media forums like Twitter bring people from divergent backgrounds together under one house? How about a constitution for the citizens of earth?

If you can't demilitarize earth, and if you can't unite the people of earth, are we doomed to fight more wars? When will the wars stop?