I'm generally credited with a fair imagination, but I can't quite imagine how Riddley Walker could be filmed and still retain even a hint of the linguistic mastery it contains.

As a post-apocalyptic tale, it's plenty strong and original, and maybe, just maybe they could convey some of the savour/saviour, wud/would/wood, heart/hart genius, but...

Well, I'd be more than willing to be astonished, surprised, thrilled. Wonder who could direct such a thing. (It's my unconfirmed opinion that Joss gave Wash the name "Hoban" as a tribute, by the way.)