And it is also about whether an ancient grievance is about to simply disappear, dissolved not by victory on any side, but simply by having become economically unsustainable.

Maybe, but I bet the decline of farming is fertile ground for new grievences.

Alos the formulation of protestants versus catholics isn't as ancient as one might think. If I understand correctly it was fostered in the aftermath of the rebellion of 1798 in order to split the nationalist Irish along religious lines. Before 1798 non-Anglican protestant Irish were considered Irish and wasn't given special priviledges, but after they were accepted into the protestant and anti-catholic community.