There's been a great deal of speculation as to which of the Hergé books will be adapted for Tintin 2, and we finally have a clue that at least narrows the field of possible candidates. Screenwriter Anthony Horowitz responded to a question on Twitter with a hint about what fans of the first movie might expect to see in the sequel.
Calculus first appeared in Red Rackham's Treasure, and went on to appear in Destination Moon, Explorers On The Moon, The Calculus Affair, Flight 714, The Castafiore Emerald, Prisoners of the Sun, The Seven Crystal Balls, Tintin and the Picaros and The Red Sea Sharks.
Red Rackham's Treasure was one of the books adapted into The Adventures of Tintin: The Secret of the Unicorn, so presumably the sequel will be based on one or more of the nine other books listed above. Either way, we should probably all brace ourselves for at least one whimsical invention like the clothes brushing machine or the wall-bed, as well as plenty of deafness-related jokes.
Call me sick, but I'd really like Calculus to be voiced by Gilbert Gottfried. I think that would make for a truly entertaining film.