This finale should be amazing. Possibly the best season yet, or at least right there with season 2, depending on how this ends. Here's my lines I would set on odds of biting the bullet this Sunday:

 
Black Singer chick +150
Eli +200
FBI agent Knox +200
William, Eli's son +450 (Only if Eli survives, I feel like 1 of the 2 will go, but not both)
Narcisse +500
Chalky +600
Patricia Arquette +750
Harrow +1200
Van Alden +1500

With O'bannion already killed this season, none of the other characters playing real people should die. My guesses are my first 3 I listed on there. Eli would be the big one, but he seems to have run his course as a character. I have a feeling the Narcisse/Chalky feud will continue for another season. The Chalky and Harrow characters are both so popular and still somewhat being explored, so I would be surprised to see them die.

as a bonus, Mickey Doyle +800. Probably won't even be in the episode at all, but I can't stand that character and am surprised he is somehow still alive.

Title of the finale is "Farewell daddy Blues" by the way....