I also think that's why it's very hard for competitors to compete. As soon as one is going to get credibly menacing they'll improve on the quality again to preserve their position.
I think that has happened with McDonald's for instance. A few years ago the quality was at it's lowest, the food definitely started to feel fake, air filled and not satisfying. Since the small local competition of hand crafted hamburger popped up a bit everywhere, and credible international competitors ramped up (5 guys, in n out...) they had to improve the quality. And my impression is that it's been a bit more than a year that the quality dramatically improved, and their hamburgers actually taste like food again.
I think it's simply the quality versus profits cursor and it can be adapted any time.