“Brexit” is a neologism for the case that the UK decides to leave the EU.
According to the Treaty of Lisbon (Article 50), “[a]ny Member State may decide to withdraw from the Union in accordance with its own constitutional requirements. A Member State which decides to withdraw shall notify the European Council of its intention. In the light of the guidelines provided by the European Council, the Union shall negotiate and conclude an agreement with that State, setting out the arrangements for its withdrawal, taking account of the framework for its future relationship with the Union.” If no agreement is reached, the membership simply ends 2 years after notification and the state is completely on its own.
So, provisional course of events:
~ the UK-EU estrangement continues
~ the UK government is politically forced to call a referendum
~ a majority of voters is against British EU membership
~ notification is served
What will/might happen now? Just a few aspects:
~ according to the estimations I’ve seen, the UK pays about 8 bn € to the EU and the benefits of its membership are an est. 80 bn €. Is that nearly correct?
~ the European Economic Area (EU plus Norway, Iceland, Liechtenstein) allows N,I,L to participate in the common Internal Market of the EU; but they are obliged to adopt all EU legislation related to the single market, except laws on agriculture and fisheries. Would the UK try to stay in the EEA?
~ In discussions, I have often seen the claim that the commonwealth nations, esp. Australia and New Zealand, harbour much goodwill to the UK and would grant them highly favourable status when it comes to trade. Is that realictic?
~ Even more commonplace is the mention of the special relationship with Canada and the US. Is it true that the wellbeing of the UK is of high importance to US politicians and voters, say, comparable to the fate of Israel?
~ In Newspaper commentaries, quite often NAFTA is mentioned as alternative to the EU. How easy would it be for the UK to enter NAFTA?
~ The financial sector is very important for the UK economy. Would non-membership in the EU make London less or more attractive as international banking place? Is there a significant difference if the UK is a member of the EEA (thus unilaterally subject to EU regulations) or not?
It is really hard to find scenarios that are free from national sterotyping and wishful thinking. Perhaps the SDMB is the right place - go at it, but please stay civil and try not to base arguments on Napoleons policies.