In a better (i.e., non-Mafia/non Michael Corleone) world, Frankie might have had a case for survival because of how Michael manipulated his loyalty:

Michael was at his most manipulative after the Tahoe shooting. First he played Tom's emotions like a violin ("I always wanted to be thought of as a brother by you, Michael"), then he scared the rs**t out of Frankie at Frankie's home--then said he wanted Frankie to "help me take my revenge." "Michael...anything," Frankie practically collapsed with relief. Michael sent him to put his head in the lion's mouth by meeting with the Rosatos--to suit Michael's purpose. If he settled the problems with the Rosatos, it was one more worry off Mijchael's mind. If the Rosatos killed, or tried to kill, him, it was further proof that Roth was behind the Tahoe shooting.