Even if Sal was successful, he would have died once Vito got out just like what happened to Di Maulo, Gallo, etc. Once he made that choice to take over he sealed his fate even if Desjardins didn't kill him and he killed Desjardins first.
Maybe if they hadn't started fighting inside their own group (Desjardins vs Montagna, and Di Maulo doing nothing and acting like he was permanently asleep even when Vito was already out to get him), they would have killed Vito, not the other way around. Vito was powerful, but not bulletproof, imo it was more the lack of organization among the "conspirators" that brought them down.
