It’s not clear the EU is imploding, but let’s just say it were, or that it will. That still makes “remain” better than “leave.” As the implosion proceeds, the United Kingdom would end up with a rather gracious out, and one which does not drive Scotland away, once other nations would start leaving or radically paring back the terms of their participation. Along the way, “ever closer union” would not be a threat to sovereignty. Conversely, if the country votes for “leave” in June, it will be perceived as yet another domino in the cascade of anti-globalist nationalism and would bring a rather sudden shock to London as a financial center and relations across the Irelands.
Look at it this way: there is no general case for being the first rat to leave a sinking ship, if that ship has stores of food. And the United Kingdom, with its own currency and set of distinct historical traditions, can leave whenever it wants and resort to its perpetual life raft.
Option value! It’s not enough that leaving be better than staying. Since “wait and see” is an option, leaving has to be much better than staying, given the mathematics of the expected value of irreversible decisions. I just don’t see that case has been made.
Here is my earlier post on Brexit.