  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.
