Probably no way to tell until somebody that's knows decides to tell
The clans might have stayed intact while their activities might have slowed down enough that nobody paid attention.
Then during different periods of Italy's history,like maybe under Musolini,they just couldn't be as powerful and thought to have been extinct.I think at some point the Camorra was thought to have dsappeared

Probably like in America where in certain cities,their "black hand " activities gave way to Prohibition and then Gambling. Words like Mob and Syndicate replace words like Maifa,Camorra,Black Hand.But in reality although they changed businesses and started working with other ethnicities.,they were still secretly intact families.Probably expose by Appalachia