Suppose Tessio’s plot to have Michael killed on his way to the Barzini meeting had succeeded. What would have happened to the Corleone Family principals? IMO:

--Neri would be killed at the same time or before Michael. He was loyal to Michael, was his bodyguard, and was of no use to Tessio..
--Clemenza would be an immediate dead man. He was loyal to Michael, hated Barzini, and would never accept an arrangement with Tessio (not that Tessio would have offered him anything—there has never been a co-Donship). Rocco would have to be killed at the same time, or before, Clemenza.
--I think Tess would have asked Tom to stay on in an advisory capacity, certainly not as consigliere. He was the repository of Vito’s and Michael’s political contacts, which Tess and Barzini would need to provide protection for the drugs trade. Tessio was smart enough to see that Tom—lawyer, non-Italian, not in the muscle end of the business—would be useful to him with politicians and judges, as he had been to Vito and Michael. I think Tom would accept. Though he was loyal to Michael, his personal relationship with him was tenuous; he was a pragmatist (willing to convince Sonny to make a deal with Solozzo if Vito died); and, let’s face it, he didn’t have a life outside the Corleones. I also think he knew that if he said no, Tess would have him killed—he knew too much to be on the loose.

Tessio’s the odd man out in this fable. He knew Barzini was stronger than he was—as he said to Vito in the fishtank scene: “Forgive me, Godfather, but with you gone -- me and Pete'll come under Barzini's thumb.” Barzini may have promised him that he’d be autonomous in some way, but I doubt he’d want to make Tessio the new Don Corleone—a rival—especially since he’d betrayed his own Don to get there. Once a traitor, always a traitor. I think Tess would be a dead man sooner or later.

What do you think?