1) The cause of a united Ireland will be back with a vengeance. We've become used to polls showing that a large chunk of the nominally 'nationalist' community in Northern Ireland are content to remain in the UK for the time being. That may change rapidly if the Irish border becomes the frontier of the EU.
2) The centre of gravity in what remains of the EU will shift a little to the left. That's simply a question of basic arithmetic - the bulk of British members of the European Parliament are right-wing (more UKIP than Tory), and Britain casts a right-wing vote in the Council of Ministers, which is effectively the second chamber of the EU legislature. (It used to be said that even New Labour was the most right-wing government in the EU, although admittedly that was before the admission of the former Eastern Bloc states.) Our representative on the European Commission is also a Tory.
3) Much of Labour will become totally disorientated, because a belief in Britain's European destiny is part of their DNA. Their instincts will be screaming at them to campaign to get back into the EU as soon as possible, but they won't want to be seen to overturn the referendum result straight away. They may settle on a compromise position of going all out to keep Britain in the European Economic Area, on the same basis as Norway and Iceland. That would at least make it easier to return to the EU in future decades.
4) David Cameron will resign as Prime Minister. I was never entirely convinced by the claim of John "the Gardener" McTernan that Cameron's position would have been untenable if there had been a Yes in the indyref - but this vote is one of his own choosing.
5) The Tory party will not split. Ironically, there's much more likely to be a schism if Remain wins by a narrow margin. Most Tories who vote to Remain will be easily reconciled to a Leave outcome, because they're mild Eurosceptics anyway. The handful of genuine pro-Europeans in the party will probably feel that Cameron did his level best.
6) The powers of the Scottish Parliament will effectively increase. There may be a Sewel Convention preventing Westminster legislating on devolved matters, but that doesn't apply to the EU - and indeed EU law always has primacy. The Scottish Government's freedom to act on devolved matters will therefore be much less constrained if Britain is outside the EU.
7) There will be a second independence referendum in Scotland. I make no prediction about the outcome of that referendum, and clearly there are one or two people in the SNP (such as Kevin Pringle) who think it will be harder to make the case for independence if Britain has decided to withdraw from Europe. But as long as Scotland votes to Remain and finds itself outside the EU against its will, the case for a referendum will be unanswerable, because we were endlessly told last year that a No vote was a vote to stay in the EU.