Current policy is that transatlantic air carriers wishing to serve Ireland must operate at least an equivalent level of service to Shannon as to Dublin. This is designed to ensure that Shannon receives at least 50 per cent of direct transatlantic services to — from Ireland. The policy is enshrined in the Ireland-US bilateral air services agreement.
This policy of course applies only to transatlantic services. Within the European Economic Area (EEA) airlines are essentially free to operate on any route within the EEA without any restriction on frequency, capacity and fares. Outside the EEA access is governed by the provisions of the relevant bilateral air services agreement.
The question of whether any airline wishes to exercise traffic rights available to them is a matter for the airline on the basis of its own commercial judgment.