Don't believe the "play-by-the-rules" bullshit. Mob bosses were getting killed left and right in the 50s without any retribution. Genovese's biggest mistake was picking someone who got rattled around the ring too often to do the shooting.

As far as Costello goes....Vito didn't intend to kill him,if he had,and Chin actually was the shooter Chin never succeeds in his ride to the top,instead he takes a 'ride' the same night one way.If the move was to kill him regardless of the shooter he dies if he was successfull.It was a delicate piece of 'work' by some one well trained not to kill him.
Costello's shooting was a bargaining tool.Nothing more,nothing less.It was also some very intricate political stuff,Alberts murder was Vito's give back for Carlo's support.Probably the other 3 bosses as well.

YUP!

1.If they missed the first time they should have been able to get the job done over the next 16 years.
2.The commission was all powerfull at the time and killing Frank means death to all involved.Vito died in 69.....Miranda when???Catena???Carlo???
Point being they all died of natural causes.
3.What is never written about is that they were on the 'mattresses' for a year or so before the shooting.Very uneasy 'calm'.All the 47 and 54 guys laying low.Frank gets 'shot' and everything was put in place where it pretty much remains today.

Vito didn't have much of a fan club ,what he had was animal instinct to survive and was a stone killer.He kills Costello he gets clipped.He lets Costello live he has a bargaining chip.

No more moves on Frank and no moves on him.Plus Carlo becomes boss and they become allies by attrition.

Vito doesn't get his just due.All the 54 guys were 'his' hand picked choices.Frank was busy with the opera and Keafaufer.Probably the best graduating class in the history of Cosa Nostra....one foot in the past[tradition] and one foot pointed in a new direction.Vito bought in a Jersey guy as his under[Catena] and kept a mustasche as his consigliere as to not alienate the old guard and the NY guys.He brings in as his under a guy with so much money he didn't need the top spot and to much smarts to want it.....life without looking over your shoulder by design is a sign of genius.Plus he gets wired in nationally to the old syndicate,especially to the Jews who were shaping Vegas.Lansky was a Costello crony,Catena wires Vito in nationally where he hadn't be really welcome.He could blast through walls but using a door is easier,and Catena had the key.He was smart enough to choose Catena and that makes him a great boss if he never does another thing.Another thing is that Vito understood that a system of checks and balances is essential to maintaining power,so he created this shifting sands delegation of authority.I don't know if he sat down and planned this,doubt it.But in retrospect it is pure genius.He was dead 43 a month or so back and you can still reach into the well of the administration and find his thumb print all over the place.
Pic