You`re spot on EI-BUD. Norwegian are cutting their winter services to Belfast, Cork and Shannon because of their precarious financial position. They cannot afford to sustain losses on routes in the winter period. A Cork-New York with a hub carrier would work well. There are 500,000 people living in Cork (city & county). Shannon has far less population yet has numerous transatlantic services.
Both Belfast and Cork have the same challenge in attracting a hub carrier for transatlantic services. They are similar sized cities though Cork is obviously more prosperous with a lot more industry, especially US firms in pharma and IT. Both cities should be able to attract a hub carrier if Shannon can.
Norwegian have cut SNN-PVD however increased SNN-SWF to daily. If Cork cannot find a carrier to operate a sustainable transatlantic service within the next 10 years, that could spell the end of that dream as the M20 will be open by then.