If Norwegian long haul is granted an Irish AOC then i can't see the Americans not granting traffic rights, Norwegian is a massive Boeing customer with a fleet of around 87 Boeing jets and another 120 Boeing jets on order.
Norwegian could fairly quickly replace the Thai crew with Spanish crew if required to satisfy European employment rules, plus it has already recruited American cabin crew and some EASA licenced American pilots, so i don't think this story is going anywhere, they (American unions ) might not like it, but its an open skies agreement.