st patrick, you must remember the Shannon stopover requirement was only dropped a couple of years ago so Cork was prevented from having a scheduled US service during the boom times. It also has the current disadvantage by having a relatively short 7,000ft runway.
Let's remember Shannon has several carriers flying to the US and the Shannon region's population is about half the population of Cork city & county so I think it is likely a US carrier will fly into Cork once the economy improves on both sides of the Atlantic.