I just said the code they use for this game is the same for every console and we play on a ported copy which doesn't take much to do, so they do not have to worry about changing the code per console and the only things they change are asset models for some weapons but this is only for last gen and wouldn't require much coding but would require extra modeling. To keep a game online all the time they need servers obviously that are capable of handling tons of users and the database at the same time which they have a separate team for so this shouldn't hinder progress on content. Let's have an example, let's say Bungie decides they wanted to add a new area in a mission like they did with the spindle, they would have to model/create the new area (which isn't done through code they have a map creator which is drag and drop mostly just like every game engine almost and this is assuming they aren't reusing an area) then code the triggers to open the area once a certain task is completed, which again only needs to be coded once because destiny is using the same code for every console, then they test it on their computers to make sure it is playable and works, then they port it over to a developer console to further test it and finally push it to the live game. This alone would take them half a week probably less and would provide players something to do for 1-2 hours depending on how difficult they make it assuming it's something like the spindle mission, do they do this? No. Would doing something like this benefit the game? Yes, and wouldn't take them much effort to accomplish.