The Black Armory is part of the new Season of the Forge, which will begin on December 4, 2018. It will be followed by the Season of the Drifter, followed by another unnamed season. Season of the Forge will add the new The Dawning event, new Crucible content, and new weapons. Annual Pass holders who can access the Black Armory will get Light and Fury weapons, the new Forges of the Chain activity, a Raid Lair, Exotics, and Legendaries.
The blog also noted a set of changes coming to the PvP/PvE hybrid Gambit Mode. Infamy will be more readily available, with Infamy rank point awards for all bounties being doubled. Various challenges have been retuned to be easier to complete and a new bounty rewards Primeval envoy kills. Ranking up in subdivisions will award Legendary weapons and armor. Plus the players who receive their Primeval second can only receive one “catch-up” stack of Primeval Slayer, rather than multiple stacks based on performance.
Bungie suggested the transition into the next year of Destiny 2 will come with its own changes and plans for the future. The company has previously said it has a full year of content planned following Forsaken. Black Armory will be the first piece of content for Annual Pass holders and more free content for everyone is coming.