There is a compromise for Scotland that I haven’t seen mentioned. It would satisfy those who want to leave the EU and the UK, and those who would only want to leave the UK. That is, EFTA membership with EEA membership for Scotland.
Norway (and others) would most likely veto a UK membership of EFTA. The trade block has 13 million citizens today, and allowing the UK back in would create a serious imbalance with a UK population of 65 million. Particularly if they allowed in a new member with a difficult relationship with the EU.
However, Norway would most certainly welcome a Scottish membership of EFTA. Scotland on its own has a comparable population size, and there are a lot of things which the two countries could cooperate on. From fisheries to oil exploration.
It would also solve some sticky problems that would come with an EU membership for Scotland, such as the question of a hard or soft border with England and Wales. Also, there would be no pressure to join the Euro. The kids would be enrolled in Erasmus and the universities would have full access to Horizon20.
Sweden, a member of the EU, and Norway, a member of EFTA, have a long-standing passport union along the same lines as the Common Travel Area that operate in the British Isles. It’s a union all Nordic countries belong to, whether they are in the EU or not. It is a union that predates EU membership for any of the Nordic countries.
The down-side with a Scottish membership of EFTA would, of course, be the one that Norway complains about. Scotland would have to accept rules and regulations decided by Brussels, without any direct input on those rules and regulations. It would have to pay a membership fee into the EU budget.
Scotland wouldn’t be represented at the European Council or in the European Parliament. It would be, as some uncharitably put it, a democracy by fax. It’s a situation that would please nobody, but it would be a middle road that would give Scotland the things it needs – access to the single market – while also placating those who wants complete independence.