I wanted to write out some scenarios for the UK’s departure from the EU to put out there and see if there are others.
Some of the legal aspects are noted here, for detail.
1a. Temporary EEA
Likeliest now, I think, is a temporary EEA arrangement which becomes accidentally permanent.
The new PM could suggest EEA (“Norway Model”) as a solution to maintain access to the Single Market and keep the UK together while limiting harm on the City (this may already have happened), and the EU could agree to this quickly as it has the effect of swiftly removing the UK from the EU while limiting economic damage. There is not a lot the EU could do about this because it is a matter of fact that the UK is in the EEA and has expressed no desire to leave it. While it would suit both sides to deem this arrangement “temporary”, it may in fact become permanent.
1b. Permanent EEA
A deliberate negotiating for an EEA arrangement is less likely, as it may tempt other countries (notably non-euro Sweden and Denmark).
2. Swiss Arrangement
The EU would probably quite like the Swiss arrangement, of case-by-case bilaterals. This would cause severe damage to the City, with finance sector jobs moved to Frankfurt, Paris and Dublin.
It would take a very long time to negotiate, however, and would cause significant division and disadvantage within the UK. Some may feel it would becalm those who made immigration the issue more than the “Norway Model” would, but that assumes they can be becalmed at all…
3. Absolute Exit
The rise of populism in both the UK and across the EU may tempt a complete divorce. This would be utterly economically and socially calamitous to both sides, however, and would almost certainly herald the break-up of at least one of them.
4. Remain in EU
Yet this remains possible. Once the new PM invokes Article 50, the UK is out in two years even if nothing has been agreed in negotiations. Such a calamity may be put back to the people as “Remain an Associate Member of the EU or Leave completely and herald utter chaos”, although even then I wouldn’t want to bet which side would win.