Worth noting that Apple would almost definitely prefer to have their European HQ in London where there is far more talent available for cheaper, but it would mean they would have to pay 25% vs 15%. Same can be said for Paris, Berlin, Madrid, or even Stockholm or Copenhagen. Ireland is an expensive place to do business, but they're the only country in Europe that's big enough for a large MNC HQ whilst also not charging extortionate corporation taxes. If European countries got their act together, cut spending and cut taxes in line with Irish, Swiss, Singaporean, and UAE rates they would be much more competitive.
Will they just find some way to give the money back?