Destiny 2 will be available on Steam on October 1, 2019 with a new free to play tier. Existing players will be migrated when the game is ready and all progress and achievements will be safe.
There is a new Shadowkeep which is intended to be released on October 1 in sync with the new Steam release. The new Shadowkeep returns to the moon like the game originally started off at.
Bungie has done an excellent job with the Destiny game and the expansions have make the community of players extremely happy. The game has been rebalanced several times as the developer attempts to copy with the varying skill level of players.
Once the migration is complete its not unreasonable that even more content for Destiny 2 will be released given the impact the game has had over the last 2 years in the MMO first person genre.
While the game will work on a 2 GB video card, best bet for this game is a 8 GB card so that it can be enjoyed properly. The game also needs 105 GB of room on the SSD for installation.
Hopefully there will be someway to avoid downloading the game all over again. Not many have internet speeds of 1 gigabit or more.