It will be changed in two very important ways. First, the 27-nation European Union will have fractured into separate groups of 17 and 10. Second, the economies of the Gang of 17 will be centrally managed by a Franco-German coalition, while the nations among the 10 "leftovers" will fight a losing battle to effect the policies of the EU of which they are paid-up members. Peaceful coexistence between the 17 and the 10 is no sure thing.
The American colonies went to war to break away from Britain, and fought under the banner, "Taxation without representation is tyranny." The excluded 10 will have to decide just how long they want to tolerate marginalization before deciding that regulation without representation is equally tyrannical.