So far every DLC has tied into lore that already pertained to the original content within destiny, Crota was mentioned several times, Oryx was mentioned a few times in vanilla and once more during the dark below if you returned to eris after killing crota, and the house of wolves made a proper appearance when we met with the queen initially. These dlc events didn't just come out of nowhere and existed in the destiny lore beforehand most likely due to cut content after the original supercut of the game was put down. But that brings a problem into Rise of Iron, we all know Saladin was holding the iron banner tournament to train us but we were never told anything about a machine plague, AND we know damn well the warlock order would've had Saladin's head if he had withheld that kind of information. Now you could make a connection with osiris since Shaxx has been in communication with the cult on Mercury and that Saladin bequeathed the information to Shaxx to pass it on to the Vanguard before he went back out on his nearly month long patrols. I don't like new information being revealed in a place that is located so close to an existing area in the game be completely ignored within the original content in a universe this big. I mean the Vault of Glass has more connection to the universe than this plague does since the Vault was the vex's attempt at recreating Oryx's throne world. This seems like bad storytelling on Bungie's part but maybe we just don't have enough information about this plague and it's placement in the destiny world.