Brexit: Britain leaving the EU could be a messy divorce

"There is no shortage of problems facing the EU, so having the British problem to deal with as well is going to be one more thing that the EU could do without," said Ian Bond, head of foreign policy at the London-based Centre for European Reform. "It would add to the kind of loss of self-confidence that the EU suffered with the 2008 economic crisis. It never really recovered."

Britain's departure could make the EU "more defensive, more cautious about undertaking radical reforms that might actually provoke other countries to say: 'Well this is not actually the direction that we want to go in,'" he said. The likely winners if it is an exit? The far-right political movements, which are already making major gains in some European countries amid concerns about the EU's inability to manage the migrant emergency and prevent attacks in Europe's capitals. For them, said Bond, Brexit "would be a success, without question."