Northern Ireland is dependent on having an open border with the Republic, and also has an agriculture-based economy.

Some of the possible (likely?) Brexit outcomes mean a closed border with customs posts and the end of agricultural subsides or the ability to sell agricultural products cross-border.

There is a clause in the Good Friday Agreement for referendums on Irish reunification: http://www.thejournal.ie/united-ireland-border-poll-3136932-...

I agree that the open border is important for those on both sides. Personally I was hoping that the political leaders of both the UK and EU would start the negotiations by aiming for common ground and establishing some good faith, and the Irish border would surely be one of the areas where everyone could agree a high degree of openness was in everyone's best interests. Alas, they seem to be doing the opposite so far, and now we have this new spanner in the works.

I meant the odds of Scotland or Northern Ireland leasing the UK may have been different than what the voters thought in the referendum. Or to put it differently: if there had been a third option in the referendum of "Leave, but only if it can be done while keeping the UK intact" how would that option have done in the referendum? (ignoring whether it would be practically possible to have that option).