Flavor physics beyond the Standard Model and the Kobayashi-Maskawa legacy

The Kobayashi-Maskawa (KM) hypothesis about the existence of a third generation of quarks represents a cornerstone of the Standard Model (SM). Fifty years after this seminal paper, flavor physics continues to represent a privileged observatory on physics occurring at high energy scales. In this paper I first review this statement using general effective-theory arguments, highlighting some interesting modern lessons from the KM paper. I then discuss some novel extensions of the SM based on the concept of flavor deconstruction: the hypothesis that gauge interactions are manifestly flavor non universal in the ultraviolet. The phenomenological consequences of this class of models are also briefly illustrated.