Just my opinion and I could be wrong but I feel the demise really happened when the Cleveland Family went down a wrong road in the narcotics biz.
Before the drugs were ran by independents and ghetto lords like Herman Stephens.
In the Greene trial,they only found Cisternino and Carrabia guilty. Thats it.
Carmen Zagaria really brought down the family. The drug trade brought in paranoia, inexperienced workers and too much greed. Then Zagaria flips.
His testimony locked up Licavoli, Lonardo.
Joe Gallo had all the makings of a good underboss..he got life.
Tommy Sinito knew how to earn. He was sentenced at 22 years.
The whole Greene ordeal would have been squashed if John Nardi would have been made.
If Nardi gets made,then you have no war. Greene would have been a afterthought. Heck maybe he gets outed as a informant.
Clevelands's problem is that they never had a plan B or enough to supplement their losses. They could never overcome the Zagaria flipping, and when the Vegas skim stopped,their went a alot of $$$$ out the door.