I've only commented in the early pages of this thread. Has anyone thought of a counter argument to both the OP and the idea Karin Murphy will be completely sidelined because she will probably have a major role; perhaps the major role, to play in getting Harry out of his gig as the Winter Knight? Before they went into the old meatpacking factory to meet Nicodemus, Murphy told Harry that she didn't believe there wasn't anyway other than death to get out of being the Winter Knight. So that raises the question of how Harry could do that.
After Harry flash froze then blasted apart the Sidhe noble who gave him some lip at his birthday party at Arctis Tor, Mab commented, "No one has lifted a hand to them that way since the days of Tam Lin." So who is this Tam Lin guy? The wiki page about Tam Lin is somewhat sparse, but he has dealings with Mab; who sometimes is called Maeve and other odd spellings. Eventually Tam is going to be sacrificed by the sidhe, but he is rescued by a mortal women who hides him; and there's some shapeshifting involved. The main thing is that Tam is free from Mab and can go about seducing mortal maidens, which seemed to be his regular pastime.
My guess is there is probably more than one story about Tam Lin and Jim will adapt whatever he needs in order to tell his story, but I'd bet dollars to donuts Karin Murphy won't get completely put on the sidelines.