How much taxes will be paid in the EU when the giants leave? Ireland is making a judgement here, one where they understand that they have more to gain this way. That is: unless you are trying to make the claim that they have been bribed by Apple.
I don't think many megacorps are going to willingly abandon a fifth of the world's GDP and an even larger portion of the world's disposable income. They aren't going to leave that much money on the table.