I suspect that the disunited UK might well be on the change thanks to Brexit. The reunification of Ireland might be on the cards, which would solve the border problem, but that requires a referendum and we know what trouble they can cause!
In the meantime, Scotland may secede and rejoin the EU on its own behalf. I would wish them well.
England and Wales become little Britain and out of the EU. Everyone is happy.
As far as Judi's OP goes - peace in Ireland: It's anyone's guess. As per the linked article - "It is completely unknown".
However, terrorists have been carrying on since the GFA, at a much lower rate, thank goodness. They haven't gone away and they never did need much of an excuse. It's what terrorists do.