Examples: EU constitution, Ukraine-EU treaty
I suppose it is harder for the Netherlands to leave because they were foolish enough to sign up for the euro.
There are two western european countries who pay a lot into the EU who arn't in the euro - denmark and sweden. Both might decide to leave to protect themselves by leaving.
Those layers of gov by independence or by super state are increasing gov cost. Never reducing it. If they believe to beat automation with this trick politicians are desillusional... There will be a little resistance from the judges but the machine will win. Constant data awareness at an exponential rate of acquisition