So, starting with Mavericks, Apple said that the naming convention would be based on places "special to Apple" (specifically, places in California). What do you think the next OSX version should be called?
Anyway my theory is they will have adventure sports theme to the places. They'll tend to be local knowledge place not normally on the map and the names will all start with M.
That's actually a good guess…. since Apple tries to portray itself as an "eco-friendly" company. Sierra resonates with the Northern Cal hippies, hipsters and outdoor adventurers. The people that shop at REI. Apple's kind of people. 🙂