This post does an interesting analysis of changes happening in Ulster and what might become of it. As the Catholic populations grows and the Protestant population declines, there are a number of scenarios of what might come next, all thoughtfully explored in the piece liked to at Bigthink.com.
As progress was made in Ireland and Northern Ireland, it is easy to imagine it forget about it and assume it is stable. Perhaps it will remain stable, but change is coming, one birth at a time.
(Map shows the areas in Ulster with a majority of Catholics (green) and a majority of Protestants (Yellow).)