I assume that Apple always thought US corporation tax was due eventually. After all, they borrowed something like $40 billion in order to pay dividends - while holding something like $150 bn in off-shore funds. They were just hoping for a tax holiday, like was given in the dot.com bust to get US companies to invest some of their off-shore cash piles then.
Most damningly of all, they announced the week after they lost the Irish case, that they were going to repatriate just about the exact amount of cash to the US that they'd be able to offset all the US corporation tax against their bill to the Ireland. Clearly as a way of trying to generate a conflict between the US government and the EU about all the tax revenue the US were "losing".
But clearly they took the fucking piss with the bit of the tax plan where the Irish tax authorities signed off on an Apple subsidiary that had no geographical location at all, in order to avoid any tax for sales to the rest of the EU.
Personally I think the Commission missed a trick. They should have ruled that the extra tax be paid to Narnia - created a new EU state called the Republic of Narnia - and produced a giant wardrobe and then forced Cook to walk into the wardrobe with one of those massive cheques (or even a huge suitcase full of money), in order to pay it. Televised of course. Extra points for dumping loads of fake snow on him before he could walk out, or even having him chased away afterwards by a giant lion.
Sorry, am I being silly? It is Friday afternoon.