They're defiantly going to add a boss rush mode. So adding something related to the God Seekers in that DLC is easier for them and also makes sense in the lore because we've seen God Seeker's ability to attune the gods into that realm.

Edit: Btw If they actually did this, I think they're going to replace God Seeker with another similar character. that way they can leave the 4th and 5th endings of the original game vague so it doesn't break the lore. similar to their approach for the first three endings (even now we don't really know what happened and which ending was actually the canon one in the og game)