Earlier quoted context omitted.
Not really. The UK decided itself to leave the EU. The UK claims that Scotland doesn't have the legal standing to make that call itself. That's a fairly clear sign of loss of sovereignty.
Greenland left the EU, although Denmark stayed. Perhaps England can leave the EU but other NI and Scotland stay?
Firstly, economically, the remainder of the UK is a far larger market for Scotland than the EU. This wouldn't be a big issue if the UK can negotiate very good access to the single market but that's highly questionable. It also is complicated by the second point.
Secondly, it is highly unlikely that Scotland would be able to (re)enter the EU without joining the Euro. There are other exemptions the UK has that Scotland won't get but this is the biggy. It was the SNP's original economic plan to join the Euro. However, when the Euro went politically toxic following the crash, this was dropped and pretty much killed SNP's economic argument in the independence referendum. It's still pretty toxic but is probably less so given that the EU referendum has hosed Sterling.
Thirdly, a big issue in the independence referendum that hasn't gone away is that an EU entry requires unanimity and Spain are dead against separatist movements because of the Basque situation. It's possible that they will have their arm twisted by the EU commission if it means another net contributor added to the Euro block but it's not clear cut.
Fourthly, legally, they don't get to choose. They can't officially negotiate with the EU as they aren't treaty partners. Only Westminster can legally grant separation. If Scotland had voted independence the first time then it would have been followed through without a doubt. It is entirely possible the UK parliament will refuse a second time because of the outcome the first.
As to NI, all of the above and then some. The whole of the Troubles was really about NI's status in the United Kingdom and giving that up is unlikely to be a quiet affair. Maybe it won't become violent but there's more history there than in Scotland.
In short, I wouldn't even begin to know how to call this.