When I first read "Mist" years ago, I was a little put off by paranormal aspects, but when I re-read the book last year, I was struck by how much I had missed. It's a fantastic story, and I think it will make a great film. (And I hope we get a good soundtrack with some Levon Helm songs).
Outsider, Jolie Blon's is one of my favorite Robicheaux's and it would make a good picture. But my preference for a next Robicheaux would be "A Morning For Flamingos". I know this would be a prequel to Mist, but it has a lot going for it...Bootsie's first appearance, and a fantastic character study in Tony Cardo. IMO Burke's best characterization (not including the main characters) until we're introduced to Bertrand Melancon in Blowdown, which btw if I was a betting man I'd go "all in" on it (Tinroof Blowdown) being the next Robicheaux movie.
BTW, In the Moon of Red Ponies is high on my list of Burke books I'd like to see on film.