This is all speculation/wishful thinking but I do think its possible. I've been having a look through the items on destinydb.com and some of them sound rather interesting, in particular the mentions of the city consensus.
It's made me begin to think maybe we only played the first half of the game. With the abrupt ending and so much missing from the trailers maybe some of what we saw is still in there but its part two. The game ended with the black garden fight and the cut scene in the city [spoiler]with the traveller healing and starting to glow[/spoiler].
Its probably wishful thinking but maybe that's part 1 and then you get the two expansions about the hive and the Queen/fallen. We also have some events like the trials of Osiris where we might get the chance to meet a representative and learn about him. Then we might get a short part 2 of the story with parts we saw in the trailers.
The reason im thinking this is because of all the city consensus stuff. There are armours, ghost shells, class items, emblems, etc. It seems like it could be pointing towards a story point where we meet the city consensus and give testimony of what we have seen and experienced. From there we get a new ghost shell (consensus shell) and all the city vendors have new stock.
The city would possibly make some decision and give us a couple of missions which would lead to us meeting the crow and the plot twist.
The whole thing would be used to generate a bit of hype and a cliff hanger ending that gets people interested for Destiny 2 which would probably be announced not long after.
The whole thing is wishful thinking and speculation but it just seems weird their being so many mentions of the consensus if they aren't going to play any role in the game. I also don't know how they could dump so much of the content they made, or how they would get people to buy a sequel after what we've got so far.
[spoiler]
Technically speaking it would be fairly simple to do if that's there plan. All the assets are there apart from a cut scene or two. It wouldn't require any extra locations, and the only thing missing is a few mission markers and spawners. As for size It would only be a small update and since the game is online only they don't have the restriction of offline players missing out.
[/spoiler]
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According to destiny, this game will be around for 10 years so im 100% sure they will add many more parts to the story. My guess is we only have about 10% available.