I hadn't seen SCION, but just read through the FAQ and skimmed some of the Apr 2016 whitepaper. It doesn't appear to address centralization. For example from their literature: "SCION only assumes that a few top-tier ISPs in the isolation domain are trusted..." Sounds like it's trying to solve many problems, but centralization isn't one of them.

I wish them well, it's good to have lots of people working on this from all angles.