The history of shared currencies amongst sovereign nations is that the currency collapses due to political differences.
The EU is trying to destroy sovereignty and create a United States of Europe before that happens.
But what they have created is a United Nations of Europe, with all its divisions, futility, bureaucracy and waste.
Even if Brexit is somehow sabotaged or stopped, it will eventually happen as the EU will collapse when the euro does.
The EU is more like the Fourth Reich