A few more things that popped into my head - expanding on the idea that something similar to "The Bells of St. John" may have happened, could the raven have something to do with the Great Intelligence, or maybe even BE the Great Intelligence? And maybe that is who is stalking the Doctor in the trailer for next week, and that is the "them" mentioned?
I know, it looked like the Great Intelligence was destroyed in "The Name of the Doctor", but we've seen characters like The Master/Missy come back in all sorts of ways.
Another idea I had this morning:
Sleep No More was the only episode that looked like filler, and seemed to have no connection with other episodes in terms of forming part of a two-parter, or linking in to any of the continuing storylines (Ashildr, Osgood, the Zygons, the Doctor's confession etc.)
Now, one thing was bothering me:
Why did they have the sequence where Clara ended up in that "sleep chamber" or whatever it was? We didn't see exactly what it was like for her because it was from a fly-on-the-wall camera's point of view.
I don't know if there's anything that could debunk this theory, but what if this episode (and the next) will turn out to be some sort of "dream" that Clara experienced when she was inside this thing. I know they showed that surreal bit with Clara singing "The Sandman", but I like this idea too much.
The one thing that would support it could be the absence of Rufus Hound from "Face the Raven". I know, it would have been a little weird having him since he played a comic character, and that this episode did a sudden switch from being light-hearted and comic to being mostly serious and dramatic when they entered the passage. Now, Clara was mysteriously absent from most of "The Woman Who Lived", and it seemed odd that the Doctor would go there without his assistant. I know it could be seen as the result of Jenna Coleman being busy filming something else or them wanting to focus on the relationship between The Doctor and Ashildr, but if this IS a dream then certainly the absence of Rufus Hound would make sense, since Clara never met his character. He became immortal in "The Woman Who Lived", and I got the impression that he was going to form a partnership of some sort with Ashildr.
Plus the whole "Victorian street hidden in modern-day London" thing is a bit confusing, mostly with the idea as to where in Ashildr's timeline this fits in, with anachronisms like phone calls thrown into it. Have they gone back in time to something that happened in Ashildr's timeline in the 1800s, or has Ashildr from the 21st century decided to take over this Victorian street? So confusing - so maybe this would support the whole "it was only a dream" idea?
Also, there was the whole thing with Ashildr appearing in the photo that Clara got. I thought at first this would be later in her timeline than Face the Raven, when she'd know what happened to Clara and that the Doctor was going to hate her, so is this some deliberate message to the Doctor? Did anything else happen there that we didn't know about, which we'll see in the finale?
Does this make sense so far? I'm just putting down thoughts as they come to me.
So I'm wondering if at some point the show will cut back to the middle of "Sleep No More" from Clara's point of view, or we'll find that there's been a whole sequence of Clara narrating a dream to the Doctor?
I know the whole dream sequence idea is the no. 1 cliché for undoing events we've seen on screen, used as a cheap way out ever since "Dallas", and used a LOT on "Medium", which I think gave me the next idea - the notion that maybe Clara is being given some sort of warning that someone is after the Doctor's confession, and that at least some of these events reflect something that will happen (I don't know how she would have got them? Some sort of special quality of the devices from Sleep No More, or somehow the ghost of River Song is giving her messages. Maybe it's going to be like the whole "Who composed Beethoven's fifth" idea, with that "something happened, and the Doctor only knew to avert it because he was told what happened" (i.e. the ending of "Before the Flood"). That is, because they were in the future, technically the all the things would have happened in the past and...
I think I'm probably rambling a bit here, and getting over-complicated, but I know Moffat does stuff like that and I hope this all made some sort of sense.
Also, I thought it was kind of strange they didn't choose to do completely silent end credits like in "Earthshock", but then I don't think that happened in "The Angels Take Manhattan".
So to sum up my essay I'm suggesting the clichéd "It was all a dream" idea - it's the simplest way for me that they can stop the TARDIS from being a memorial to Clara and possibly one way that the Doctor can get off of wherever he's gone - after all, he LOST the teleportation bracelet. The only other ways would be some sort of intervention from Missy or the method of travel imposed on him by the Time Lords in "Genesis of the Daleks", which I think is one of the few storylines I've ever seen where the TARDIS did not appear at all.