Shadowkeep does not include anything from year 2. No Forsaken, no annual pass. Starting with season 8, when Shadowkeep launches, there will be individual season passes for the four seasons that will make up year 3. You get one pass with Shadowkeep, which will be for season 8 (or whatever the current season is, for people who buy it after season 8). If you buy a season pass, and log into the game during a season when you already have a pass active, your new pass will be credited towards the next season, so if you buy the basic Shadowkeep, you get a season pass. Log in during season 8, and the pass will be active for that season. If you buy another season pass, and log in during season 8, that second pass will give you access to season 9.