My understanding

by stabbim , Des Moines, IA, USA, Tuesday, February 19, 2013, 18:25 (4298 days ago) @ Xenos

Yeah I find it pretty unlikely that existing story/missions will just disappear. Sales-wise, it would be a colossally stupid way to do things - only the people who bought in near the beginning would be interested in your story - people would have no incentive to buy the game down the road. The only way this wouldn't prove true is if the story is so empty and inconsequential that no one cares to start with. Which isn't really the Bungie Way.

The UI elements we saw in the ViDoc, even if they are placeholder, suggested to me that story chapters would probably be like Spartan Ops episodes in Halo 4 - coming out on a schedule, but still available later.