Man, I'm telling you folks, as a Halo fan: The word of mouth around Destiny is not positive. It sold amazingly well, but its population numbers will drop off a cliff.
The competitive suite is not sustaining players and people are already fed up with the repetitive nature of the missions and raids. Halo 4 was the fastest selling game in franchise history but the community wholesale rejected the game, and the word of mouth surrounding it was not good. This lead to declining player population to almost nothing (relative to what past Halos would pull) by the end of the year. I suspect something similar will happen with Destiny.
The one wrinkle in my comparison is the kind of hooks Destiny has, along with the upcoming DLC. If I'm wrong - which is possible - it will be because Bungie made fundamental changes to loot, and infused compelling content into a game which sorely needs it. Bungie are smart game company so they're never truly out of it. But they have some work to do.