How this Tintin Movie Easter Egg limited the franchise?

I am a huge fan of Tintin, and the 2011 movie by Steven Spielberg and Peter Jackson, but there is an easter egg that limits the entire Tintin movie franchise, if they plan to do one. When Tintin is searching for the magnifying glass, the camera pans on some newspaper articles that relate to earlier Tintin books, such as Cigars of the Pharaoh. But this means that it already happened in the movie timeline, so they can't do any solo Tintin film. I actually hoped that they would make two Tintin films of the beginning solo ones to develop characters, to make up for the Thompsons lack of appearance in the 2011 film. But I am still pumped for the next Tintin film, please let it be happening, all the collaborators' easter eggs are really bugging me.