I just think the fact marathon is simply a mode, extraction and that's about it is going to forever limit that game so I don't think a forsaken/taken King moment is even possible.
Like someone I was listening to said Destiny just had it all, I remember logging in and just the world of that game was brimming with content. When's forsaken dropped you had just content in every direction, pvp, strikes, patrols, guns to chase, events, it was absolutely just loaded with things to do.
Marathon is one element extraction, can't even load in and just go tdm, or domination, no chill content, no strikes or anything to just kick back... Nothing. And like someone said you can't have it up end extraction, so it's so limited.
To me what division did was that right way to incorporate extraction, it was merely an optional mode in a game with a good bit to do and even then it's not like that game exploded.
I think bungie is screwed