In 67 BCE, tensions between the brothers Hyrcanus and Aristobulus over who should be King of Judea erupted into the Hasmonean Civil War. This conflict lasted until 63 BCE, ending with Hyrcanus on the throne and Judea a Roman client state.
But how would things change if the widely unpopular Hyrcanus died before he could ascend to the throne? Would it prevent the civil war? Would Judea be able to maintain its independence, at least for a time?
Of course, the circumstances of his death would be important. Him being murdered would cause a considerably different reaction than if he died of an illness or accident. But I leave the cause of death up to you. Whether he dies from being poisoned or just choking on an olive, there would be some significant butterflies.