The flavor composition of high-energy cosmic neutrinos has long been recognized as a rich probe of particle physics and astrophysics.  We are rapidly making progress in measuring the flavor composition with higher precision.

To take stock of the present situation and of things to come, I chose what I think are some of the most interesting flavor-related questions, and laid them out according to when we will answer them and how easy it will be to answer them.  (Of course, there is some subjectivity involved in where the questions are place.)

Fore more information about the status and future prospects of flavor composition, see my recent talk at PAHEN: Flavor in high-energy cosmic neutrinos: Interpretation and new challenges.