I haven’t really looked into this. Perhaps Raga will weigh in and contradict or validate it. New gear says that the Drifter is Eli, Dregden Hope. And he is working with Dredgen Vale, who was once known as Shin Malphur. They’re working together on Gambit (with the approval of the Vanguard). The implication being that they’re trying to harness the Darkness, maybe create a new kind of grey Guardian.

Again, haven’t looked into it at all, that’s just stuff I saw while reading that Reddit thread. It’s interesting speculation in any case.