I hope the writers are setting up false expectations, and Lumen will be back full-time next year. If they're setting her up for death, they telegraphed it with the subtlety of repeatedly punching me in the face in last night's episode.
Also, Peter Weller sure was offed rather quickly. It's a good thing Dexter is only suspected by crazy people. If Weller had just called the police, who knows what would have happened.