Any agreement would require ratification by all member bodies. Whilst Germany, France et al do a lot of trade with Britain, the likes of Romania hardly do any, and us leaving closes the door for their citizens to live and work here. Only takes one state to say no thanks. What's more, the Spanish prime minister recently said that it's hard to see how British expats would remain in Spain should we leave. The idea that all member states are similarly beholden to Britain is a little arrogant.
You're advocating a position based upon next to nothing in terms of certainty of outcome, whether it's future trade deals, the management of EU/British citizens here and abroad, the reaction of Scotland/Wales/Ireland to Brexit, the length of time take to negotiate any subsequent arrangements and so on. And that's even before you look at the very real threat of how other countries in the world will respond to Britain leaving.
That last point is something that is ignored by the leavers. Hollande has the worst ratings of any French President in living memory, with the terrifying Le Pen gaining ground. If Le Pen did get into office, it seems likely that she would push to leave the EU too, leaving Germany as the last remaining huge economy remaining. It's hard to imagine they would shoulder responsibility for leadership on their own.
Add to the mix that much of eastern Europe is still heavily reliant on Russia in terms of energy, and it's not that far fetched to imagine Putin sat there rubbing his hands ready to capitalise on any chaos that ensues to try and snatch back the Soviet Empire from a Europe where the main two military powers (Britain and France) have upped the drawbridge.
Could you say that such a scenario will never happen?
