No need for scepticism on this I don't think. From Spain's point of view, he is clearly one of the candidates, having managed at youth levels here and as people are seeing is very highly respected. It is totally possible that he could get offered the role and Spain pays any compensation.
Would Karanka want it at this moment tho? No, I don't think he would, I think he is too young and has far too much to offer day to day in training etc that he will want to stay in club football. One day tho, very possible.