I think Furio would kill himself or return to Italy permanently before he betrayed Tony.
I don't see Christopher doing something stupid enough to get whacked over. He could easily be demoted though. But on the other hand, with Ralphie dead and Paulie going over to the other side, Tony is going to be very short of capos. I think it's more likely that Adriana will get Chris in trouble with the law and that is how his situation will be resolved. Jail or witness protection.