Destiny 2's upcoming Season 17 had been shrouded in mystery until the official trailer was leaked, with Bungie then deciding to share official information about what this new release entails. Season of the Haunted as a name was leaked early as well, but there was a lot of doubt concerning its validity seeing how it was only used in Bungie's CMS. Now that it's official, Destiny 2 fans also know a lot more about Season 17, including its main characters, what sort of story threads it will pick up, and the possible rewards obtainable with the various activities.
As the name suggests, Season of the Haunted takes place on the Moon, but it also features a new patrol zone in the form of the Leviathan ship. The Leviathan had been absent for a long time from Destiny 2, and Calus is now returning to the scene with a new plan to gain more power -- possibly, one that will allow him to become one of The Witness' Disciples, much like Rhulk from the Vow of the Disciple Raid. Still, the fact that the Leviathan is now drawing power from the Moon's dormant Pyramid ship may be no coincidence, as it could hint at Bungie's plans concerning the release of the Lightfall expansion. Namely, it could be the premise for Shadowkeep getting vaulted.
Why The Leviathan Might Be a Sign That Shadowkeep is Being Vaulted
The Leviathan was the first location in Destiny 2 to host a Raid, eventually hosting multiple of them before being moved to the Destiny Content Vault for story reasons and to save precious space when the Beyond Light expansion launched. This first session of content vaulting also included four patrol zones and the various maps based on them for Destiny 2's activities, and story-wise this was motivated by the fact that the Darkness' Pyramid ships had entered the Solar System, obscuring those planets.
It's worth noting that the Leviathan is a planet-eating ship that could end up consuming the Moon when Lightfall launches, thus providing Bungie with the perfect excuse to vault the Shadowkeep campaign and its main location. Lightfall's release will most likely come at the cost of older content being moved into the Destiny Content Vault, and Shadowkeep is currently next in line after The Witch Queen. In fact, Destiny 2's Tangled Shore from Forsaken and the expansion's campaign were both vaulted to make room for The Witch Queen, making it all the more plausible that Shadowkeep will meet the same fate.
There are not many reasons to go back to the Moon in Destiny 2's current state, and while Season of the Haunted provides one such reason, seasonal activities are always removed when the big yearly expansions are released. This doesn't necessarily mean that the now-returned Leviathan will be removed when Lightfall launches, as it is a ship that could move elsewhere in the galaxy, but it could still devour the Moon in order to further Destiny 2's story and also allow for an easier transition when Shadowkeep is vaulted.
Shadowkeep itself is also not the best expansion in Destiny 2's history, and while the Moon is a very iconic location thanks to it also being part of the original Destiny, it being removed will likely hurt less than locations such as Mars and Titan. Also, because Bungie has already done something similar with those planets back with the introduction of Beyond Light, it's not unlikely for the company to do it again with Season of the Haunted and Lightfall - this time vaulting the entirety of Shadowkeep instead.
Destiny 2 is available on PC, PS4, PS5, Stadia, Xbox One, and Xbox Series X/S.