It was recently reported that Bungie has started development on Destiny 3, and that they don't want the second game turning into a dead live-service game. What a this means for Destiny 2 and the ongoing Fate Saga is unclear, but one possibility is that more content will be vaulted. To avoid this, Bungie could follow the model of World of Warcraft Classic, and release a new game with most of the older content. In both editions, access to all destinations could be free, while access to the expansions' campaigns, endgame activities, and exotics requires owning and installing them.
The new game could be released in 2027 to celebrate it's 10th year anniversary. To keep sizes in check though, this Light & Darkness Collection would be limited to the 9 campaigns, 8 regions of space (including 14 destinations, 21 strikes, 39 crucible maps, 6 gambit maps, 5 protocols and 4 arenas), 14 endgame activities within destinations (7 raids and 7 dungeons), Crucible, Trials of Osiris, Gambit, and the exotics (expansions and seasons) from the Light & Darkness Saga. As it replaces the New Light Legacy Collection, licenses carry over to access campaigns, endgame activities and exotics.
However, this would leave the New Light experience fairly empty. To make up for this, Bungie could make all 5 destinations (including 16 strikes and 27 crucible maps) from the first game, and the 5 endgame activities set within them (4 raids and 1 dungeon) available. Moreover, the campaigns, destinations and endgame activities from current and future expansions -if they're not moved to Destiny 3- will also be in the game. Together, the old and new destinations fill up the director screen nicely, removing the portal's need. With the removal of some dungeons, the respective Dungeon Keys transfer to Silver.
Lastly, the Leviathan could return with the 10th Year Anniversary Pack, with the Star Horse from Bungie's 30th Anniversary Pack serving as in-universe explanation. With the destinations from these pack, the total of free content is brought to 1 campaign, 8 destinations (including 16 strikes, 30 crucible maps and 3 arenas), 11 endgame activities within destinations (6 raids, 2 raid lairs and 3 dungeons), and the Crucible and Trials of the Nine modes. To keep file sizes manageable, as most players don't own everything, installing destinations, campaigns and endgame activities becomes optional.
A new medium
Another way to revisit the Light & Darkness Saga is by adapting it for the big screen. It would tell a slightly different story, as it wouldn't include the player surrogate Guardian. As the games are the player's story, this adaptation heads into a different, darker future. Instead, the movies would focus on the most important characters from the saga: Cayde-6, Eris Morn, and Elsie Bray. Other characters would be Ana Bray, Zavala, Amanda Holliday, Mara Sov and Uldren Sov/Crow. A companion tv show based on the Golden, Dark and City Ages could provide background on these characters.
Destiny: The Taken King opens with Cayde-6, not the Young Wolf, clearing the Skywatch. Together with Ana Bray they activate the Array and reconnect with Rasputin. He discovers a Hive infestation, leading to Eris Morn’s involvement. Joined by Elsie on the Moon, the trio defeats Crota, only to be warned that Oryx is coming. They seek aid from the Awoken, but Queen Mara Sov will only help if they defeat the traitorous Skolas. When Skolas falls, the Awoken join the fight against Oryx, but he still breaks through, kills Mara, and enters the Black Garden. However, the Guardians still manage to defeat him.
Destiny: The Witch Queen starts with Uldren Sov staging a prison break, alerting Cayde-6 and Eris. It is a trap however, and Cayde-6 is killed. Eris follows Uldren to the Dreaming City, where he attempts to free Mara from the Ascendant Realm. Instead, Savathûn emerges and kills Uldren. Eris chases after her, but is overwhelmed. She seeks out Elsie and Drifter on Europa, where the three steal Stasis from Eramis and receive a warning from the Witness. Eris returns to confront a light-wielding Savathûn, while the others help defend the Last City from Eramis. They succeed, but Eris mysteriously vanishes.
Destiny: God of War Vengeance finally sees the Witness arrive, with former Cabal emperor Calus as its disciple. Calus travels to Neptune, with Ana, Osiris and Crow in tow, where he activates the veil, enabling the Witness to breach the Traveler. The Coalitions follow him, but only manage to defeat the Witness when his power is siphoned away. Ana and Elsie trace the energy to the Moon, where they discover Xivu Arath and Eris, now a dark Hive god, being behind it. A final battle erupts, but ends when the Traveler suddenly erupts in light, sending Elsie back in time and resetting the timeline.