As to NI uniting with the RoI I a not sure the people of the Republic would really like that. Things are pretty good there at the moment and would they really want the headaches of incorporating a population that might resort to violence. Status Quo, perhaps with direct rule from Westminster might be the best solution.
To quote an Irish boss of mine; "Its a difficult problem" his stock answer for every question by the way!
Semantics, its the place known by a handful of names only a few of them printable in CA!