Dave Cameron has fast-tracked the date of the UK's BREXIT Referendum to June 2016. Irrespective of the result, the UK's relationship with the EU will be altered, as Cameron seeks to negotiate changes to Treaties, and he has not ruled out quitting the EU altogether if these don't go well. The Dáil's Joint Committee on EU Affairs has called for Ireland to have a formal role in these negotiations, because under the GFA, the Republic has a right to be consulted on any matter affecting NI and its constitutional arrangements.
Should Britain vote Yes, then NI would be hit harder than almost anywhere else. BREXIT would have both a politically and economically destablising effect on NI. It would also have serious consequences for the Border Counties of the Republic, not to menton the Irish economy as whole, whose major export partner is the UK. European integration put the conditons in place for the GFA, as Ireland and the UK were already becoming more convergent through the EU. Business and employment, worker and student mobility,NI's access to the Single Market, CAP, structural funds and peace support would all go or be severely curtailed. A return to Border controls would equate to repartition.
Even if the UK votes No, it has signalled its willingness to pull out or redefine its place within the EU in a way which is not likely to favour NI. David McWilliams, the celebrated Irish economist, has an interesting article here in which discusses how the growing realignment of the UK and EU, ( as well as the possible break-up of the UK through a Scottish Referendum) could result in NI making a very quick decison on where its best interests lie. Demographic changes in NI mean there will be no sentimental loyalty to an increasingly remote and detached UK
United Ireland may not be as remote as it seems | David McWilliams
McWilliams also points out that when change happens, it happens all at once.
Co-incidentally, the Belfast Telegraph has also addressed this issue today, speculating on whether these shifts could be the starter for a renewed drive towards Irish reunification.
Why the EU vote could drive Catholic unionists towards Sinn Fein and a united Ireland - BelfastTelegraph.co.uk
My gut tells me that if the question comes down to the money, honey, we are going to see PUL"unicorns" in greater numbers than you could shake a stick at. The middle-class business sector is loyal to business, first and foremost. Woudn't that be a turn up for the books?