[jcranmer]

You are aware that the enlargement of the EU allowed existing countries to restrict migration from new countries, and that the UK government explicitly decided not to?

You are also aware that the EU specifically allows to limit the freedom of movement on "grounds of public policy, public security or public health"?

You are also aware that the recent migrant crisis of the past few years has caused these kinds of barriers to be raised in response? Proving that such restrictions are not just mere hypotheticals?

The European Union is, after all, not a suicide compact.

[man-and-laptop]

I'm talking about long term impact, not emergency measures. Everything you've mentioned is an emergency measure AFAICT.

For comparison, the impact of banning the printing presses only materialised quite a lot later than it happened. Remember that Europe used to be a lot of independent (and feuding) nations, rather than a union of any sort. There were unions of sorts under the Catholic and Orthodox churches, but England for instance was not part of those unions. it was in those times that Europe went through the scientific and industrial revolutions, while the empires I mentioned slowly stagnated.