It was interesting him saying the idea of national boundaries with sovereignty was kind of invented in the Peace of Westphalia. That seems to be fading a bit with transnational organisations like the EU. I'm wondering what will happen to the UK Eire border now we're supposed to be Brexiting.
This article on the history and future of nation-states from New Scientist is from 2014, so it doesn't cover Brexit, but you may find it interesting: "End of nations: Is there an alternative to countries?"[1]