When the Destiny 2 expansion pass was first revealed, players immediately recognized the two icons featured for the expansions. Having seen both a bunch of times, the common belief was the second one would feature the Warmind Rasputin and the other would have something to do with Trials and/or Osiris, the latter which Kotaku sources have confirmed.
According to their sources, the upcoming expansion will be titled The Curse of Osiris and is set to release sometime in December. The expansion will take place on Mercury, giving players a new location to patrol, with the infamous Lighthouse, Destiny’s reward for going flawless in Trials of Osiris, will be open for all.
Very little was revealed about the story, but it supposedly involves saving Osiris from the Vex, something that both match Destiny’s lore and what can be found at the Lighthouse.
With that being said, remember that this is a rumor and one that matches commonly held beliefs.