If RFK would have lived and certainly Teddy Kennedy wanted that to happen. But, not today. Party leaders like Obama, Clinton & Castro are the Dem nominees and nothing will change that.
Bobby Kennedy wouldn't have gotten the nomination even if he'd lived. Primaries were little more than beauty pageants then and had little bearing on the nomination. Humphrey didn't even enter any primaries or caucuses that year, and he still got it because he had the support of the party bosses. At that time, that was the only thing that mattered.