If Britons vote Thursday to leave the European Union, it will be a shock for the EU and the global economy and an earthquake for Britain.

Some analysts warn of a potential "disintegration" of the EU as remaining countries seek to renegotiate their own relationships with Brussels.

"It would be a shock for the EU that would require mutual assurances that the EU continues to stick together and that a very successful decades-long process of integration doesn't in the end turn into disintegration," German Foreign Minister Frank-Walter Steinmeier said last week.