Spain and Ireland have some of the highest number of variable mortgage rates in the Eurozone. Coincidentally they have also a high number of owner occupiers, Spain being the highest in Europe per capita. So any rate hikes will hurt.
Of course the peripheral states have received huge benefits from being in the Euro club, not least the ability to borrow vast sums both on world markets and from the ECB.
The trillions these countries owe are in Euros and have to be serviced in that same currency. If they leave the club it would be nothing short of economic disaster. Reverting back to their national currency would inflict a massive devaluation on themselves against the Euro. Simply impossible economically to contemplate.
In practice there is no actual mechanism in place to allow countries to leave the Euro. New treaties would have to be written and the whole of Europe would be plunged into uncertainties.
It’s for these reasons I can never see it happening.