Brexit Speculative Future

The UK just voted to leave the EU. The vote was not uniform, however, look at this map:

So really, England voted to leave the EU, Northern Ireland and Scotland voted to remain in the EU.

Maybe nothing bad will happen. Maybe the EU will negotiate some kind of free trade agreements with the UK, and there will be some talk of a united Ireland or an independent Scotland but no actual independence.

But maybe...

• 2016: UK votes to leave the EU
• 2017: Scotland votes for independence overwhelmingly. Northern Ireland votes to join the Republic of Ireland, but only just.
• 2018: Negotiations for Scottish independence break down. Northern Ireland is granted independence and merges with the Republic. Sectarian violence breaks out in Northern Ireland.
• 2019: Scotland declares independence without authorization by the UK. An election is held in England, and nationalists are elected with the promise of reuniting the UK. English troops start massing at the border with Scotland.

Now what happens? Do the Germans send troops in to Scotland to defend the territory? Does England conquer Scotland? Does the US get involved? Ireland isn't a full NATO member, but the new England would be, as the successor to the UK. Does NATO dissolve, or is there full blown war in Great Britain?