After the demise of the Avvocato, Umberto Agnelli's death marks the end of an era for Juventus, the Fiat group and the whole city of Turin. The Agnelli were often referred to as the uncrowned Royal Family of Italy, or the Kennedy's of our beautiful peninsula. RIP, Umberto Agnelli.
Juventus is still owned by the Agnelli family and there are still quite a few of the old ones alive (their sister Susanna for example) and hopefully a new generation coming up (John Elkan's name has been mentioned, but he's still very young). But Gianni really was the patriarch, and Umberto was his only natural successor.
Actually the only one who could have succeeded right now would have been Umberto's son, Giovanni, who was as brilliant and classy as his elders. unfortunately he died at the age of 33 from a rare form of cancer.