The irony is, though, even had Tessio and Barzini succeeded, Tessio's days surely would have been numbered. If Tessio was proven to be disloyal to the Corleones, how could Barzini have expected any loyalty at all from Tessio either? Someone as shrewd as Barzini would see Tessio's behavior as a deep character flaw, one that may be temporarily quelled but eventually would manifest again under certain circumstances.
In all likelihood, once The Corleones and all internal threats from within the family had been extinguished, Barzini would have had Tessio eliminated as well, replacing him with a figurehead whose loyalty had been proven and unquestioned.
What Barzini did would be close to what Lucky did with Salavtore...after taking out Messeria, he took out Salavtore because he knew Sal would viewed him as disloyal and already planning to have him killed. So it makes me wonder, did Tessio have a backup plan? ....did Tessio have something in place to take out Barzini soon as possible (had Vito actually been killed)?
