On the point of the south wanting a united Ireland, its in the founding aims of nearly all parties from Fianna Fáil, Fine Gael, Sinn Féin. I still strongly believe in an united Ireland and would campaign and vote that way. When I was younger I would of been of a more militant mindset but as you grow older you evolve. I have advocated for years within FF when we were in government we should of had a green paper ( no pun intended) on a united Ireland and the all institutions of the Republic have a united Ireland contingency plan the same as we did for the Euro changeover.
I was the mover of the Fianna Fáil motion that we organise and contest elections on a 32 county basis that was passed much to the shock of the leadership, I have a press release at home of Iris Robinson of the DUP denouncing me ... !!!
In a vote on a unification, it would be carried 70-30. The heart will triumph the head on this one for most voters. It would not be a pretty vote as images of the past and a billion tricolours would fly high from the poles. A simple line to be used in any vote " Did Wolfe Tone, Robert Emmett, Padraig Pearse, James Connolly and Michael Collins die for Ireland not to be an independent and united nation". The old 26 + 6 = 1 would get an airing too.
The problem is as time goes on, it gets further and further away from 1921. It pains me to say but I do feel differences when I chat to northerners. Any united Ireland will be a long process not an over nite thing as suddenly 20% of an united Ireland would not want to be part of it. I can see where a joint sovereignty would apply for a while and slowly like Britain with Hong Kong, they slowly withdraw.
An another interesting thing is and for the Union to survive, they need to start wooing Catholics into Unionist parties ... as slowly but surely the demographic tide turns against protestantism. The more Orange riots the better in that case and flag protests. There was an interesting article in the Irish Times at the weekend about this http://www.irishtimes.com/life-and-style/the-catholic-unionists-1.1461624