You haven't thought this stuff through.This is a tax on non-residences. If you have the resources to have/own/keep a 2nd property, then you have the resources to pay the tax on it.
You are liable for the NPPR if you bought into a boom time estate in Carrick on Shannon and now find yourself in massive negative equity, forced to move elsewhere for lower paid work to service the mortgage and renting a room in a house somewhere.
This person (and there are many of them by the way) is fully liable for the NPPR on their "2nd property" which they CANNOT sell and possibly CANNOT find a tenant for!