Good analysis. I think Tony Magi is still alive because contrary to others hasn't dropped his guard and is under 24/7 protection. People have tried to get to him after Vito's return. As for Mucci, he was close to people of the old Cotroni faction but seemed to have chosen to stay neutral during the war. He was even threatened to chose the anti-Rizzuto side. I've also been one of the few who believed Di Maulo wasn't actively participiting in the take-over but I don't think he was neutral either. He may very well have been killed because he didn't do anything to stop Desjardins.
"It was between the brothers Kay -- I had nothing to do with it."