It appears that many airlines do not wish to even discuss new routes into Cork due to the possibility of having to go head to head with Ryanair. Tomorrow Evening Echo is said to feature an article outlining the chances of Cork getting a transatlantic service. I would say slim and none as long as it's owned by the DAA.
Don't blame them. What have Ryanair done for Cork over the last few years. Start many sun routes that are already operated by other carriers. Milan BGY is the only route FR have done that is of benefit to Cork and the region.
As SNN has USPC there is not much chance a US carrier would pick Cork.