Just to make the point with the wang waving between, the British and ROI.
Both have historically had and in the future will have little influence and control on NI, it is what the communities in NI decide to do.
If the communitees in NI decide on a certain course of action, be it peaceful or not (hopefully the first), nothing London and Dublin can do about it’s control it.
Has noone learned anything from recent History, NI is ungovernable if one part of the community puts it mind to it.
London and Dublin, playing with fire and very underestimating of the Pandora’s box that could be opened that they have proven in the past they couldnt and never hope to control. It’s massively hubris to think otherwise IMO.
Put a border up, see what happens. Have a referendum on a U.I. See what happens.
Both countries are playing with forces beyond their control IMHO.