For those interested, this is an article published yesterday regarding the practicalities for the land border on the island of Ireland with regard to brexit.
The Irish Border and Backstop Explained
It outlines three possible options that may constitute the choices ahead (personally I think there are more than three, but these ones may be more realistic than any others).
One option that I admit I had hardly given any thought to, is that in certain circumstances the EU might feel compelled to exclude the Republic of Ireland from it's trading regime. From what I understand it would take a no deal brexit, and for the Republic themselves as well as the UK to have basically no border between them.
I suppose that option would add up to the EU abandoning Ireland because circumstances, historical and geographical would preclude a border in Ireland, and the EU would feel they had no choice.
I believe that problem is the reason the EU simply won't re-open or change the Withdrawal (yet to be an) Agreement.
If the EU is seen to abandon the Republic of Ireland in this way, all the lenses re focus quite dramatically. There will be many in the Republic of Ireland who would harbour huge resentment against the UK if 'option three' became the new reality.