The producers said that the villainous Morgan le Fay will not appear in the show, but that next week’s episode will go into the back story of the first Dark One who they jokingly referred to as “Steve.”
So it’s not Rump centric but its dark one centric. YAY!
I think that article might have misquoted what Adam and Eddy said at the panel, as I was there. I recall them saying that we would see the first Dark One later, but I don’t believe they said next week. In fact, they said that next week’s episode would be Arthur’s backstory, which adds up with all the behind the scenes photos from when 504 originally filmed.