Everyone I spoke to last year agreed the Irish government doesn't want reunification: they can't afford Ulster's welfare state, or a protestant separatist movement. Everyone also agreed that politically, they can't openly oppose it if a referendum happens. irishtimes.com/news/politics/…
If this is correct, then the Irish government may not want reunification, but may not be able to stop it, either--and if Northern Ireland gets special status, as now looks much more likely, that could give a big boost to the nationalists, who already have a demographic tailwind.
That said, a hard border could also easily have given the nationalists a boost, so not clear there was any Brexit outcome that didn't make reunification look more likely in the long term, though probably not in the next five years.
