This is fully speculative, so keep that in mind as you read this - Empire Magazine sat down with the Brothers Coen about TRUE GRIT, and they were asked about what's up next for them. As usual, they were coy and guarded, but one of the suggestions by the article writer made Ethan say, ""Funny you should ask, yes, we're working on a couple of scripts now, one of which it would be fair to call a full-on horror movie. Frances McDormand is the monster."
Not sure if that last part is a joke (it probably is, but who can say?), and obviously the Coens go where the wind takes them, but the horror genre is a genre the boys have definitely not taken on yet. They've come close, and they don't shy away from violence and gore. You could call A SERIOUS MAN a kind of horror film (it was for Larry Gopnik, for sure) and there's the human monster of Javier Bardem's Anton Chigurh, but they haven't jumped full-fledged into the genre. I'd be curious what kind of horror film the Coens would make. The possibilities are limitless, whether it would be a supernatural horror film, a slasher movie, a haunted house story... Obviously it's too early to imagine.
Also, their idea of a "full-on horror movie" might be different than anyone else's. People have accused the Coens of being misanthropic, almost to a fault, but I don't think that's true. They put people through the ringer and we respond to that because we care about the people they're throwing around, and although they can take glee at punishing their characters it doesn't mean they're being hateful just to be hateful. They're trying to get a response. Plus, anyone who has RAISING ARIZONA on their résumé has to love their characters. So I'd imagine if you're a character in a Coen Brothers horror film, you can probably expect to squirm a bit at the very least.
Again, this is a speculative piece, so who knows what the Coens will deliver next. It's just interesting to think about. Thoughts? Just remember, Joel and Ethan always put one in the brain.