RYR are upsetting the Irish govt over Belfast City, I think not - it is in a different country!
Different jurisdiction of course (ergo no tax implications) but I'm not sure the Irish government view it as a different country, afterall they operate a PSO to LDY.
I don't think there will be any PSO servies in Ireland apart from (possibly) a Derry - Dub - Donegal - Dub - Derry type rotation
The load factors on LDY-DUB are very poor (average 9 pax) - it will get the chop also:
the government is broke