I think they killed Furio's story line when they wrote him off the show. As I understand it, the actor was leaking spoilers and they found out. The boss David Chase whacked people quick for that.
I think that Furio characters was useless after the naples episodes and Chase only deleted him without killing him on the screen.
The relations with the Neapoluans were ruined because of Furio, I remember that a man appears with the tail in a church in the episode in Paris, Carmela is he going to tell Tony?
Also I noticed that when Tony has to kill Phil Leotardo, it is not him who calls Annalisa but Silvio, I do not understand the reason since the boss is Tony and to kill another Mafia was him to talk to Annalisa, maybe Tony thinks that Annalisa protects Furio?
