Speaking as Irish Catholic here - has none of you noticed the small matter of the majority Unionist community in NI?
Have you not noticed how very slim that majority is, though? The most recent Assembly elections, which postdate the referendum, resulted in a tie in seats between Unionist and Nationalist: in that sense, there's no longer a Unionist majority. The DUP were 12,000 first preference votes ahead of Sinn Fein. That's all. And we all know which way those demographics are going. It certainly isn't the case that Catholic=nationalist necessarily (or that Protestant=unionist) but equally, this is entirely unchartered ground.
Also, while I totally sympathise with your desire not to have to pay for NI, and as a British taxpayer I think it's perfectly fair for us to keep subsidising the place, it would hardly be Britain just dumping NI. It would be the people exercising their democratic right. Would be pretty outrageous for Britain to fail to respect the decision of the majority in NI if that were to reunify, no? Which is a separate issue from whether ROI wants it.
And for those talking about polls upthread, it's true that only 25% of the NI population now want reunification. It's also true that the figure was a 5% increase from pre-referendum.
www.irishtimes.com/news/ireland/irish-news/sharp-rise-in-support-for-united-ireland-survey-reveals-1.2784882
And this was pre Article 50 triggering, pre the virtual complete ignoring by May of the situation in NI for the past couple of months, pre any impact of Brexit really being felt.
I do not take the view that Brexit is automatically going to lead to reunification, that's an over-simplification. But the vote has undeniably coincided with an upsurge in Irish nationalism.