It is a good idea to store seeds in a safe vault but I donot believe that these vaults are really safe if they can not bear global warming issue, like you mentioned Permafrost melting. This remember me the story of Titanic. It was claimed that Titanic is such a master piece it will never sink. On the first visit the ship was sunk. So in my honest opinion it is not a good idea to spend 13 million USD for the storage of seed vault. May be Norwegian government easily bear the huge expanses but being the inhabitant of third world country where people donot have basic facility can afford such vault. Any way collecting 1.0 million seed is a big achievement. All the best for more collection. Thanks for sharing