I view this as an opportunity for the EU governing organization and would suggest that they take some of the following steps:
1)Push for an immediate Article 50 invocation rather than waiting for 3-6-12 months of dithering and uncertainty for markets and currencies across the EU.
2)Take a hard line and insist that all trade and related treaties and agreements be re-negotiated by some set date to be established at the time of Article 50 invocation.
3)Provide Scotland and Ireland the opportunity to retain EU membership either with or without their secession from the UK with the caveat that they would be required to abide EU treaties and agreements with respect to the balance of the UK.
4)Move to firm up currency markets and tie those more closely to EU countries without concern for GB Pound.
5)Aggressively push for stabilization of the rest of EU countries without regard for effect on the UK.
This would send a very clear message to others that are discussing exit referenda that if that is a path chosen that the EU will use it's scale to close out non-members. It would also isolate economic instability and harm to those that choose to exit.