Could I suggest in relation to the discussion about relative populations in various points like Cork, Belfast and Shannon. This topic its largely irrelevant.
The USA is the source of the lions share of passengers, holiday makers and VFR in the main.
let's remember Shannon has a hugely established transatlantic reputation. Tour operators in the USA use Shannon and Cork is not yet featuring heavily. This may be due to lack of frequency, and then established trading arrangements ex Dublin and Shannon. There is good business traffic opportunities in the Cork area, such could sustain a service, but as mentioned Norwegian is not in the frame for any of this...
Cork, IMHO needs one of the USA large network carriers to offer a daily rotation to a large US city, ie EWR/JFK. They need to offer a wide range of connections, cater for business traffic, and stick at it until it gets well known and established and onto the program of large tour organisers....