This is a very sad news to hear. Glynnis Talken confirmed to SCLegacy that she won’t reprise her role as Kerrigan. And not for lack of interest. Some time ago, Glynnis told me she was interested in voicing Kerrigan in StarCraft II.
Robert Clotworthy had told me in our interview some time ago that he would also love to repirse his role as Jim Raynor. However, as reported last november Blizzard contacted several agencies in search of candidates to audition for Kerrigan and Jim Raynor roles—clearly dispatching the former voice actors despite the wish of many fans of welcoming Glynnis and Robert back into the fold.
New actors may be hired and probably be somewhat good at the roles, but Glynnis and Robert can never be replaced. They are unique. They gave life to the characters not just with their voice, but with their passion, humor and convincing performance. I will personally feel a sense of loss when playing the game.