In Episode VII: The Force Awakens, Kylo Ren vowed to finish what his grandfather started. But Darth Vader eventually turned away from the dark side of the Force and appeared in astral form beside Yoda and Obi-Wan Kenobi.
Andy Kluthe and Andrew Bridgman explain at Dorkly that the crisis might have been averted if only Anakin hadn't been so eager to get to the party.