At this point, the person I suspect to die the most is Karen. We know that the Lelouch/Suzaku conflict must continue, but with a shot fired, someone had to have been hit.
She knows that all of Japan needs Lelouch at the moment so she can't let him die.
Karen already feels betrayed. I don't think she believes in Zero at all anymore. Despite being a half-breed herself, she knows that Lelouch is fairly important as Britannian Society goes.
She felt strung along. She has known he wasn't Japanese for a while, but she didn't expect him to be a high ranking (or at least formerly) Britannian. That may make her do something stupid.

I'm more curious about what happens with Viletta and Shirely. The two of them both know Zero is Lelouch. Viletta will only need a short time to figure out that Lelouch is the Lelouch. If Shirely confides in Milly (which to me seems likely in light of the events) Shirely may also be told Lelouch's true identity. What will the two of these do with this information?