Burton has been talking about “Dark Shadows” for ages. He wants frequent collaborator Johnny Depp for the lead role of Barnabas Collins. Grahame-Smith follows John August, who wrote the first draft of the script. I wouldn’t bet on this being the next thing Burton does, but things definitely seem to be moving closer.
Also, if you haven’t read Grahame-Smith’s books, you should correct that ASAP. “Abraham Lincoln: Vampire Hunter” is especially exceptional.