Destiny 2: Forsaken will work in a similar way to how yearly expansions did for the original game.
The very last shot of the mini-documentary shows the game’s title card and logo, and at the very bottom of the screen, mentions that Forsaken requires both base Destiny 2, as well as its two expansions; Curse of Osiris, and Warmind.
This may come as a surprise to some, but this is exactly how Bungie and Activision have always done it. The Taken King, for example, required the original Destiny as well as House of Wolves and The Dark Below.
What Activision typically does is offer a version that bundles all previous, required content with whatever is coming next. These bundles usually also come with an in-game item that players can use to boost their character level up to the required expansion level if they want to play the new content immediately.
There’s been no such bundle for Forsaken, at least not yet. Bungie took to Twitter to clarify that there will soon be “additional D2: Forsaken product options” for players who do not own the base Destiny 2 and both expansions. These options will be revealed closer to launch.
There will be additional D2: Forsaken product options unveiled later this year for players who do not own the Destiny 2 base game and both Expansions. They'll be available closer to the Sept 4th launch.
— Bungie (@Bungie) June 5, 2018
Destiny 2: Forsaken is out September 4 on PC, PS4, and Xbox One.