Oh I don’t think for a second that anybody really thinks it will see a return to the Troubles of the past.
It is just that one side don’t want a border in respect of national unity and because it being removed was a cornerstone of the peaceful idyll in which we now co-exist with the Hun, also the ease with which people around the border can live their everyday lives, whereas the others don’t want a soft border as they want to be treated like the rest of the UK and to be separate and removed from the EU. By having no border they are really just staying exactly how they were before the vote and they know you are effectively wiping your hands of them.
I can remember the border between Newry and Dundalk the first time around and it was a massive pain in the *******s. I don’t want a border because it will be a massive pain in the *******s.
Of course there will be isolated incidences of trouble but one would expect that.