Bear with me I'm not well verse with having speculative discussions.
Here's my speculations:

  • Since Zhuge Liang's campaign vs Nanman is set at 225. Checking at who's reigning at the time: Liu Shan will be Shu-Han's faction leader (married to Lady Zhang), Cao Pi will be Wei's faction leader (married to Lady Zhen with Cao Rui as faction hier), and Sun Shan will be Wu's faction leader (married to Lady Bu with Sun Liang)
  • Meng Huo will be faction leader of nanman tribe and will be married to Lady Zhurong
  • New officers will appear and since this DLC favours the designated heroes, most of the additions will be at Shu-Han: ex Guan Xing and Zhang Bao (Shu-Han)
  • Since the events appear to circle around the Prime Minister, I would like for Lady Huang (Yueying) to appear.
  • Sima Yi will already have position in Wei imperial court. Zhang Chunua, Sima Shi and Sima Zhao will be available officers. If new events include surrender of Shu-Han, Lady Wang (Yuanji) would become an available officer.
  • Due to the period already being three kingdoms, they maybe subdivided to multiple faction leaders. (But that's risky