Well, there is a lack of killing. My guess is as you said there could be an Arso and PB or even 5 Coven members. I'm just getting spooked here because it feels like the calm before the storm.
At first I thought that we were dealing with all the coven members too. But, I mean just coven feels weak. No one was killed by the potion master, so clearly that role is missing. The Necromancer didn't use the vig role of Odd, so maybe he was blocked, or not in the game.
I have a strong feeling that the Necromancer is Drago.
There could be 3-4 coven members. If there's no Arso or PB, there could be vamps. But I find vamps unlikely for now.