No tax on profits, no sales
If Apple want to play silly games and pretend that the profits aren't made in the countries that provide their sales revenue, then let's just close all Apple stores in Europe other than in Ireland until this "misunderstanding" can be sorted out - they aren't making any profit, so no harm, no foul. Since the tax hasn't been paid, all licenses issued by Apple to consumers are invalid and using such products should be ruled illegal. Users should be offered the ability to continue using such products by applying directly to their national government to pay the 12.5% on Apple's behalf. Apple is practically a religion anyway; for its supporters, it will be like handing round the collection plate for this "worthy" cause.
In short, if Apple want a sales/tax war, we should give it to them. There is no obligation to allow Apple to sell products in Europe. Tim Cook may not have noticed, but it's not just infrastructure, education and health that suffers when companies don't pay a fair share. We have a global problem in the Middle East causing millions to have to flee their homes, and the US is no small player in this affair. We need responsible global citizens (companies included) to play their part so that we have the resources to fix these issues and deal with the consequences for those innocents so adversely affected. Shame on you Apple - you make M$ look like veritable angels by comparison.