StarCraft: Heir of Adun is the proposed name for the sequel to StarCraft: Queen of Blades.
Blizzard Entertainment has been working on an outline for a possible novel. They have no planned release window and are unsure if they have an author signed up. However, Aaron S. Rosenberg's name has been frequently linked to such a project. He asserted in 2006 that there would be a sequel to Queen of Blades, but as of 2011, this does not appear forthcoming.
A number of similar novels have been propsed by Aaron Rosenberg:
StarCraft: Tassadar's Sacrifice is a proposed novel by Aaron S. Rosenberg and alongside Invasion of Aiur, foremost among the list of ideas he'd like to write for the StarCraft universe. It would theoretically be a sequel to Queen of Blades, Rosenberg hoping that the novel would set a level of anticipation appropriate for a possible sequel.