As someone said on tumblr, last time we got a promo shot in a pizza shop and then there was never any pizza....Could be they're just trolling.
Although I doubt it would be true, maybe we will get a period BLUE as a 2015 Christmas special.It would be okay if it were a dream sequence, but I hope it is not a time travel or Dr. Who connection.To have them do a Victorian case would really show fans if they are both capable of carrying Holmes in his own time period.
Maybe they'll be attending a 'Victorian theme party' or a 'Victorian themed event' in the next episode?
I really hope its the Victorian Themed Party idea that Mr. Chirravoori mentioned! That was what I thought too and the more I think about it the more I like it! "a Victorian Themed Murder Mystery Dinner Party where the murder is unfortunately real" has been done a thousand times, but I think it would be nice to see what Moffatt and Gatiss do with it tying the new and old Sherlock Holmes together! I think it would be great fun! :)
A Murder Mystery Dinner Party where a murder occurs would be retreading TSoT, imo. Been there, done that.