Can’t see why people are naming Blood Meridian here. It’s just a western.
It would be difficult to watch due to the graphic violence and some film makers might shy away from this but there is nothing in the narrative structure of the book to make it ‘unfilmable’.
Whilst I agree there is nothing in the basic narrative of the book to make it unfilmable, the fact that the violence is so intrinsic to the nature and meaning of the book that to film it without would be to miss the point, and very essence, of the book.
I, for one, would not be interested in seeing a “watered down” version of the book, and it would not do the source material justice.
Conversely, it would also take a very deft hand to bring out the atmosphere and imagery of the book, and the majority of modern directors seem to have difficulty balancing violence with subtlety and beauty.
I did wonder if the Coen Brothers may be a good choice: The way they did No Country for Old Men was impressive, and showed signs that they may be able to take on Blood Meridian. I doubt it will happen though.