I think there is a (slight) chance we might see Lumen again in the final season next year, but they might as well not go down that road. Depends on where the final season will be going.
I currently have two theories on the final seasone, one is that he goes for the "full family man" exit, focussing on Harisson and maybe even getting Astor and Cody back (and perhaps someone like Lumen might come in play there to try and talk some "sense" into him
). Another theory I have is that he might also become a victim of his own trait .. like a Trinity killer 2.0, who actually outsmarts him .. who's to say!