Hey everyone. I've been pondering all this new art (portraits, hero units, etc.) and have thought of a theory about what will happen in Zeratul's mini-campaign...I believe it is 4 missions long.
1. Ulaan: Zeratul ventures into the caverns to find out about the Xel'Naga and fights Kerrigan but escapes with some new mystery...Which leads him to
2. Aiur: Fighting a gigantic horde of Zerg, he reaches the remainings of the Overmind (why the Overmind portrait is in the game...There is an Overmind tendril in the game as well...datamined from the beta), and...TASSADAR! The latter has flash-frozen the area (like Zamara did in the novels) before his death and now his memory and personality are transferred into Zeratul, who in a way is like Tassadar/Zeratul now. Tassadar has learned of something while connecting with the Overmind's mind and warns Zeratul.
3. Shakuras: Zeratul goes to look for help from the Protoss leaders. He probably also meets preservers here.
4. Xel'Naga space platform: Urun, Mohandar and Selendis accompany Zeratul to look for a X'N space platform near a supernova. They investigate it for clues as to what plagues the future of the universe when the supernova gets critical and they have to escape while fighting their way off the platform before the supernova explodes. Zeratul then goes off to warn Jim Raynor while the Protoss leaders return to Shakuras to warn the other Protoss and prepare.
Also, I believe the Mobius foundation is the Confederate remnants or that Valerian is behind it. (Remember that Blizzard has said Valerian would openly work with Raynor while his father never would?)
And in addition, I also believe we'll have a flashback mission with Kerrigan (perhaps the famous mission on Tarsonis where she is left to die?)