Yes, Eoin Colfer is going to write a 6th Hitchhiker’s Guide to the Galaxy book. Adams’ widow hand-picked him, apparently. He’s best known as the author of the Artemis Fowl books, which I’ve never read, so I can’t do much to handicap the odds of his work being any odd. “For years I have been finishing this incredible story in my head and now I have the opportunity to do it in the real world,” Colfer says. “It is a gift from the gods. So, thank you Thor and Odin.”
Sounds Adamsian enough. Colfer makes a much longer statement here, at the BBC website.
I know for an absolute fact that I read Mostly Harmless, the last Hitchhiker book that Adams wrote himself, but I have no memory of it whatsoever. Apparently it ends on something of a bleak note, which a sixth volume would presumably mitigate. Personally I’m of the opinion that this kind of franchise extension isn’t always a bad thing, and anyway, worst case, it can’t besmirch the greatness of the originals. (Not everybody feels this way. A big-time fantasy writer once told me that he never writes down any of his plans for future books in his series, in case some hack gets hired to finish them after he dies.) Now that it’s been a radio play, a book, a TV show and a movie, I think the Hitchhiker’s universe has shown it can take some mucking around with and keep on giving.
Though I’d be surprised if Colfer can top the ending of So Long, and Thanks for All the Fish, which felt absolutely definitive to me. Maybe Adams should have left it at that.