I understood there were two be two more. Anthony Horovitz was hired and actually wrote the sequel, Prisoners of the Sun, in 2010-11 and the final one was to be based on Alpha-Art (not sure if that was scripted). That Jackson is now talking about making movies based on The Silmarillion and is in rights negotitions with the Tolkien estate as well as his various restoration projects is an indication Tintin isn't his focus.