"Come on, it's time to turn you into a 'César'."
And that's the end of the Adventures of Tintin; he faces the dreadful fate of being transformed into an icon for the ages.
It's fairly obvious what would have happened if Hergé had lived to finish the story - our hero will escape thanks to his friends, and it's also clear that the bad guys are planning a reunion of a lot of incidental characters from previous books, some from a very long time ago. The book already features Bianca Castafiore, Professor Calculus, Jolyon Wagg, Thomson and Thompson and the Emir of Khedad and his horrible little son Abdullah. It's also fairly clear that the book would have needed a good bit of revision - there's an inconsistency in the plot between whether the art gallery is bugged with a reel-to-reel tape recorder (which would already have been old-fashioned at the time of writing) or via a high-tech microphone hidden in Mrs Vandezande's jewel. (By coincidence, a Mr Vandezande has been the mayor of our village since the last local government reform in 1976.) but the germ of a good if not great Tintin story is already there.
We also get some of Hergé's rough drafts for ways the story might have gone: drugs conspiracies based in Amsterdam, Captain Haddock's change of personality, various options for bringing back some fairly obscure names from the past. Hergé clearly saw this as a final volume, and perhaps it's better to have it preserved in mid-thought, rather than some slightly synthetic confection of a final product; Edwin Drood and Sunset at Blandings are not bad precedents.