House of Wolves
Date: March 10th, 2015
Locations: Cosmodrome, Moon, Venus, Reef
Activities: 3 Story, 1 Strike, 1 Raid, 4 PvP Maps
Comet: Plague of Darkness
Date: September 2015
Locations: Moon, Venus, Mars, Hive Ship
Activities: 12 Story, 4 Strike, 1 Raid, 1 Location, 6 PvP Maps
Bonus: New subclasses and 2 new weapon types
Vex [illegible]
Date: TBA
Locations: Venus, Mars
Activities: 3 Story, 2 Strike, 1 Raid, ? PvP Maps
Forge of Gods
Date: TBA
Locations: TBA
Activities: TBA
Destiny reddit
Image shows a bigger DLC pack called "Comet: Plague of Darkness", coming September 2015, only after mentioning that House of Wolves will release on March 10 (which does fall on a Tuesday). Next two DLC packs after Comet appear to be "Vex ???" (too hard to make out second word, possibly Vex Void, Vex You, Vex V60, or even just Vex TBD) and "Forge of Gods". Forge of Gods could possibly have to do with Cabal, but I'm not entirely sure. It appears to be very early in production.
As FWC said in another tweet, though, only a rumor.
EDIT: Original source is apparently a Bungie Forums post. Take of that what you will:
http://www.bungie.net/en-us/Forum/Post/88939979/0/0
EDIT 2: As /u/the_vault-technician so kindly pointed out, the OG OG source is from this Italian Destiny forum in which the poster claims that the photo was taken during a Bungie meeting. He talks more about Comet, saying, "I repeat: the expansion Comet (after the house of wolves) NOT 'DESTINY 2, This is just a massive DLC that will be marketed on a disk from which to make a download of destiny, is like a DLC but normal much larger and heavier."
The poster uploaded the photo towards the beginning of December. Here's the link:
https://translate.googleusercontent....zoyV7UGjIFJB7g
Everything's been translated from Italian to English so it obviously won't be as easy to read. You'll also have to scroll down a bit for the photo.
I think we can consider Comet/Plague of Darkness as Destiny 1.5. It'll include tons of new content, and that even includes three new subclasses, two new weapon types, a new base level, and a new location called "Hive Ship" all according to the image. It'll have its own DLC, Vex and FoG. I think, though, that it'll be released as a "re-release", physically, of Destiny, and that it'll include TDB, HoW, and PoD.
EDIT 3
u/Zereta also reminded us of the data-mined list of Hive bosses leaked back in October. The list includes enemies like "Gnath, the Diviner", "Cryth, the Siphon", "Noctu, the Lightslayer", "The Wall", "Voldor, the Willkeeper", "Divined Vision", "Dredge Exploder", "Storgor, the Shatterer", "The Veil", and The Oversoul. (Source:
http://gamingbolt.com/destiny-the-da...firmed-missing) At the time, we believed this to be the list of Crota's End bosses, despite "Crota, Son of Oryx" being noticeably absent. However, now we know that it obviously isn't. That being said, each name, when discovered, was tagged with "Raid" and "Hive Ship". See where I'm going with this? It would appear that this was actually the leaked list of bosses included in the upcoming raid in Comet, as, again, "Hive Ship" is listed as a playable patrol area in the photo with Comet. Therefore, it's very safe to say that Comet will revolve around the Hive. Now, as to what the Raid actually has to deal with, we'll have to wait and see. There's a fair chance that it involves Oryx, given that Eris has hinted at us fighting him through some of her in-game dialogue, though his name is absent from the list. Feel free to speculate!
except this time it's the radiance dance machines 
marcielago
. I'm trying to split my time between this and a few other games so I don't get burned out on it again. It helps keep it fresh
shottadru
yea I meant we don't run a lot on destiny 
