First expansion apparently in development.
There’s even more information from today’s Reddit leak about Destiny 2: Forge of Hope, this time about the game’s story and frequency of content updates. Again, take this all with a grain of salt, especially until someone credible (like Kotaku’s Jason Schreier) confirms it.
Chronologically, the sequel will take place after The Taken King with the Cabal attacking the Tower. The Guardians will need to fight to reclaim the Last City, eventually discovering Queen Mara Sov’s story and the true intentions of the Exo Stranger. The new raid will end with the Tower and City fighting the leader of the Cabal.
Apparently, Bungie is planning for “substantial” content updates akin to the April 2016 Update every quarter. The first expansion is already in development for Fall 2018 and will focus on the origins of Kabr, Praedyth and the Vex.
Characters won’t transfer from Destiny 1 to 2 due to the new engine but there will apparently be better character creation with the addition of facial hair, tattoos and class-themed face paint.