Destiny 2 is set to get a new expansion in: the first in its post-Activision Destiny lifetime.
Shadowkeep will once again bring about a new storyline, more dungeons (Strikes), a new raid shortly after launch, and more gear to keep track of. It'll also sport the "New Light" initiative, which basically gives away most of the Year 1 content away for free. You can preload that right now on Steam if you like, but only existing users can preload the new DLC on consoles.
As for Shadowkeep itself, it's still going to be paid content, and it's rolling out later today during the maintenance window. Bungie has noted that following a roughly 24 hour maintenance window that started yesterday, Shadowkeep is set for a 1PM ET release time, which is in line with their weekly reset cadence.
If you haven't done it yet, start the transfer process to migrate your Battle.net account to Steam! Bungie doesn't foresee any major issues, but will keep players updated if they come about. And when Shadowkeep drops, stay tuned for our coverage.
This Week at Bungie [Bungie.net]