They said nothing about "Thief not ready for release".
They said "Rogue is a Thief, but since each class need to fit in the lore and have an official guild, the thieves have evolved into Rogues"

As for another tank, they didn't mention the gun-using class so maybe we'll have a tank from an existing classes, like Lancer or Pugilist. A mage tank could be something really refreshing too