There will be no domino, only Greece is in real danger, spain and portugal are OK for sure.
Have you seen the unemployment ratings in those countries, especially among the younger generations? Have you seen Podemos in the polls? There is a very big chance of a domino effect.
I've met them, I've talked to a few them, and they don't understand much about economy. Amazingly, my last time with people with so much misunderstanding was in Germany. It's always the same story, it's about people who can't support themselves, and who expect the state to pay for their living. Spain is getting better, to my great surprise, I've met a Brit and a French who moved to Spain to work! There are opportunities everywhere...