MOTHERFUCKING END OF TIME TRAILER With the Tate and the blonde!Simm and the Dalton VO and the "My name is the Master" and OH MY GOD. I swear, I think I know what they might be going for, because Rusty is evil like that.
Based on the new "Waters of Mars" trailer, that "knock four times" sounds like the clomp of Cybermen. But in the new "End of Time" trailer, we see that it's going to involve nightmares and dreams and things not being what they seem. The blonde!SimmMaster in the hoodie is, I believe, a manifestation of the Doctor's subconscious - his Jacob Marley or Ghost of Gallifrey Past, guiding him through the nightmares. But he's also behind the latest crisis, allied with the Cybermen and with a confirmed-by-RTD returning Alexandra Moen as Lucy Saxon. Fandom is going to do a collective fist-pump if it turns out her shooting the Master in "Last of the Time Lords" actually was a Xanatos Roulette set up to bring him back if the Doctor happened to defeat him.
The thing returning through the dark might be, I hope I hope I really fucking hope, Gallifrey, which, in tandem with the dreamscapeyness, could open the door for a Romana or Rani cameo (which will make me do fucking backflips like you would not believe). If we don't get some flashbacks to the Time War (which is a possibility, because Moffat isn't in favor of showing it, so Rusty might have decided to throw fandom a bone in his last special, and we all know Tennant's a big giant fanboy), I'd settle for a few scenes set on Gallifrey (because Timothy Dalton IS playing a Time Lord). They could go for the creepy nightmare way of showing it, or alternate universe it, or any number of ways, but goddammit, I want to see Gallifrey.
IT CAN BE CHRISTMAS NAO PLZ?