Thanks for the ping! BIG Shield fan here. As fara s a "beloved character" getting written out, my guess is Claudette. I wouldn't be surprised to see Vic's ex go, too. Her role has knid of gotten in the way, IMO. From the previews, it looks like Kavanaugh wants to even the score with ex-wives, and maybe he ends up killing her while raping her.
Ahh. On second thought, the most likely character to be leaving the show is the woman officer having the baby in the car.