Destiny 2's The Witch Queen expansion is just over a month from its official release; the culmination of Bungie's efforts in making a compelling, overarching narrative. Savathun stealing the Light works based on the events that transpired over the years, but it also makes her the perfect mirror for Destiny 2 Guardians: a deadly, god-like creature with immeasurable power that can reshape the course of history. The fact that enemies of mankind have been interested in stealing the Light, like Dominus Ghaul, or desperate to find an alternative to it, such as Eramis with the Darkness on Europa, is proof that the Traveler's gift should be squandered.
However, many have died in Destiny 2 and its predecessor, with exemplar Guardians being Eriana-3, Andal Brask, and the beloved Cayde-6. Even prince Uldren Sov met his demise, only to be resurrected as Crow. While Cayde's death was part of the marketing campaign for the launch of Destiny 2's Forsaken expansion, the fact that it would happen was foreshadowed by the introduction of an otherwise anonymous sidearm: Spoiler Alert. The gun's description states that someone is going to die, and with the weapon returning in The Witch Queen, it's worth exploring the possibilities for who it might be.
Commander Zavala
Killing off Commander Zavala with The Witch Queen would make for a lot of shock value considering the Awoken leader has been a main character for a long time. With two attempts on his life during the events of Season of the Chosen, Zavala seems to have plot armor at the moment, which would make his premature demise all the more disconcerting. However, Zavala doesn't seem to be involved in The Witch Queen expansion as much as others, which would make his death disconnected from the narrative.
Furthermore, Zavala is one of the main vendors in Destiny 2, and he recently underwent changes alongside the playlist activities to make his reputation gains more in-line with the rest of the game's suppliers. As such, Zavala's death is probably unlikely, at least compared to others'.
Mara Sov
Mara Sov is one of the most powerful characters in Destiny 2, as she created her own "Bomb Logic" - a means to gain power - that directly opposes the Hive's so-called Sword Logic. Queen Mara also seemingly has a new Ahamkara egg from which a creature like Riven might hatch, and she has her own Throne World, which means she cannot be killed in the physical plane without also killing her soul in the Throne World called Eleusinia. Mara seems safe from death, but she is also a character of hubris.
With the events of Season of the Lost, it became even clearer that Mara craves power and control, even over the affection of her own brother. It's not impossible that her feud with Savathun would lead to her death, and it's not impossible that the Witch Queen is Mara. After all, The Witch Queen's original trailer stated Destiny 2's Season of the Lost is a "tale of two queens."
Petra Venj
Another likely candidate for the Spoiler Alert death is Petra Venj, the Wrath of Queen Mara and her trusted confidante. While there are no specific reason why Petra would die in The Witch Queen or in Year 5, considering this death is not necessarily occurring within The Witch Queen campaign, Petra's death could have major implications in the story. Furthermore, according to Destiny 2's lore, Mara's previous Wrath called Sjur Eido might come back to life at some point - so the void left by Petra could be filled.
Ikora Rey
Ikora is one of the leading characters in the upcoming expansion, and she is seen in the trailers investigating the events that led to Savathun stealing the Light. Ikora is a key character, but she is less pivotal than Zavala, and the fact that she took Savathun in the Last City while she was disguised as Osiris still causes Ikora grief. Furthermore, Ikora Rey's voice actor changed recently, and this might be a good indication she is either on her way out, or that there is more to come for the Warlock.
Savathun
Savathun's death could be what Spoiler Alert's return is hinting at, and while it makes sense that she needs to die to be resurrected by a Ghost, this wouldn't really be a spoiler. Savathun is shown wielding the Light and having a Ghost in promotional Witch Queen material, so it's already implied that she will die in some way, acting as a catalyst for her resurrection and the Lucent Brood. Still, Bungie did state that Spoiler Alert's return is not a coincidence, and this could signify that the death is Savathun herself.
Eris Morn
The most likely candidate among the main cast of characters to meet her demise is Eris Morn, the three-eyed Guardian who survived the infested tunnels of the Moon after falling to Crota. Ever since, Eris has become obsessed with the Hive, and she has a personal grudge against Savathun - even swearing she will be the one to kill the Witch Queen in Beyond Light. It's worth mentioning that according to Elsie Bray, the Exo Stranger, Eris is the one who became the Witch Queen in her original timeline, corrupted by the Darkness and thirsty for power and vengeance.
Another reason why Eris might be the one to die in Destiny 2's The Witch Queen or throughout Year 5 is that Shadowkeep and the Moon as a location are likely the next in line to be vaulted when Lightfall is released. Killing Eris off in the epilogue of the last Season of Year 5 would make sense leading into Year 6, as she is the only vendor on the Moon. There are several potential candidates for this death, and each of them has a set of reasons why they could fall, but the only way to find out is waiting for the expansion's official release.
Destiny 2 is available now on PC, PS4, PS5, Stadia, Xbox One, and Xbox Series X/S.