If UK votes to Leave, the consequences for all of Europe could be very damaging indeed
For the 'Leave' camp, Brexit is only the beginning. A UK vote for secession today would, they hope, eventually destroy the evil empire of Brussels and free 27 other nations from the yoke of Eurocracy.
One man's hopes are another man's fears. Former Conservative leader William Hague, once a Eurosceptic himself, has warned the death of the EU might return Europe to its dark days of poisonous tribal hatreds and beggar-my-neighbour economic policies.
Former Taoiseach John Bruton agrees. "I worry most not about the technicalities but about the destructive forces that this could unleash, not just in the UK but across the continent," Mr Bruton said. "It is the potential undoing of 70 years of statesmanship."
Can the EU survive Brexit? And, if so, in what form? Short-term collapse is unthinkable. EU leaders would attempt to close ranks against a common enemy - Britain. By making the British departure negotiations as miserable as possible, EU governments would seek to prevent the contagion from spreading across the continent.
They would fail. Brexit would embolden and encourage Eurosceptic forces of both the right and left in the EU's heartland.
In France, whatever the result, Front National leader Marine Le Pen will make 'Frexit' the core of her campaign in the presidential election next spring.
She is unlikely to be the next President of the Republic, but her message will earn her new supporters from the nationalist left. If Britain is already in the European departure lounge, she might do uncomfortably well.
A recent pan-European poll by the Pew Research Centre found a steep rise of anti-EU sentiment in almost all member states and especially in France and two of the most Europe-minded founder countries, Italy and the Netherlands.
Much depends on how the 27 - and especially core member states such as France, Germany, Italy and the Netherlands - react. There will be a chorus of opinion, led by the former French President Nicolas Sarkozy, pushing for a 'refoundation' of the EU with a 'hardcore' of some of the eurozone states and an outer, looser circle of the newer, poorer states to the east and the south.
There will also be demands by unreconstructed European federalists, such as former Belgian Prime Minister Guy Verhofstadt, for a spectacular reaffirmation of European faith. The British have gone? Good riddance, they will say. We can now 'leap forward' towards a true European government.
There is also a view, in Spain and on the French centre-left, that a British vanishing act would allow a shift away from open markets towards a more 'political' (that is, protectionist) EU.
One of the most far-seeing European statesmen, Hubert Védrine, the former French foreign minister, says all these approaches could drive the union to its ruin.
The divorce between popular feeling and the 'elites' who support the European idea has gone far beyond the borders of Britain, he says. If the 27, or even some of the 27, try to press on with more European integration without popular support, there will be a backlash that could destroy the EU.
Mr Védrine calculates that there is at most 1pc approval across the continent for the 'United States of Europe'.
There is a bloc of 15 to 25pc of ferocious anti-Europeans of left and right. There is a similar-sized bloc of moderate pro-Europeans, also of both left and right.
Up to 60pc of voters in most EU countries are now, he says, 'Eurosceptic' in the sense of doubtful about the capacity of the EU to deliver its promise of greater prosperity and its capacity to handle the Middle East migrant crisis.
To try to win over this majority with 'more Europe' or a 'hardcore Europe' would, Mr Védrine says, be "like treating an allergy with high doses of allergy-inducing products".
Mr Védrine says the EU should treat Brexit, if it happens, as a warning, not a rallying cry. A pause should be called on European integration.
There should be a 'refounding' conference to devise a more modest, practical EU, retaining some super-national powers, but focused on limited areas like trade, better management of the euro, defence, internal security and the environment. All grand plans, even Mr Védrine's counsel of caution, will be laborious and dangerous to implement, a senior European commission official warns.
"The danger is that the EU will be too divided - both divided between nations and between blocs of nations - to come up with any coherent, post-Brexit strategy," he said.
In the recent Pew poll, the most pro-EU nations were Poland and Hungary. And yet the hard-right governments of those countries believe they can scoop the free trade and free movement advantages of membership while trampling EU rules on democracy and the rule of law. The eurozone crisis has divided the EU between a struggling 'south' and a 'north' that is reluctant to bail out its 'lazy' cousins.
The Brexiteers ignore the vital role of the EU in permitting the orderly passage of the eastern European and Baltic countries to something like democratic and open societies in the last two decades. That process is not finished; it still could (with enthusiastic support from Moscow) go into reverse.
A break-up of the EU - even a division of the EU into 'rich' and 'poor' - would not be a comfortable experience for a post-Brexit Britain.
Inside or outside, the British economy would remain heavily inter-linked, and interdependent, with the prosperity and stability of its nearest neighbours.
The history of the past century suggests attempts to distance or isolate Britain from the continent have unpleasant consequences - first for the continent, then for its biggest off-shore island. (© Independent News Service)