UPDATE: New details have emerged on Sega's all-new Valkyria title, with a report on My Game News Flash being handily translated by Kotaku.
The new game is officially called Valkyria: Azure Revolution, and is considered a different series within the Valkyria universe to the three existing Valkyria Chronicles games.
Valkyria: Azure Revolution will still be an RPG with strategy elements, and it will introduce real-time combat elements as players take on the Valkyria Brynhildr, with the new game's protagonist named as Amleth. Media.Vision, who developed the third title in the Chronicles series, is behind Valkyria: Azure Revolution, which is set for release next autumn in Japan. We still await news whether we'll see it over in the west.