Some interesting discussion here. I particularly like the idea of social changes wrought by GIs (it happened even in the UK, and we were far more sophisticated) but Leej's point is also correct--there's less reason for American troops to be stationed in Ireland.
Certainly fewer troops will be stationed in Ireland, but Ireland also has a much smaller population. If, say, two million Yanks could influence 45 million English (as Thande and others have indicated), surely two hundred thousand Yanks can influence three million Irish?