When the Cannes film festival starts next week, William Faulkner's As I Lay Dying, adapted and directed by James Franco, will be in the lineup. The Spider-Man star is known for mixing bookish projects with acting in blockbusters, but has nevertheless raised eyebrows by selecting a novel with 15 narrators that tells the seemingly uncinegenic story of a southern matriarch's death and burial.

This month will also see Paul Thomas Anderson begin to shoot his version of Thomas Pynchon's Inherent Vice, the first of Pynchon's dauntingly complex works to be filmed; and Steven Soderbergh recently announced plans for a 12-hour TV dramatisation of John Barth's The Sot-Weed Factor ("If it works, it'll be super-cool. And if it doesn't, you won't be able to watch 10 minutes of it"), a rambling 750-page novel with an ill-advised title about an English poet in 17th-century Maryland.

Something is clearly changing, at least for adventurous auteurs, raising the question of whether any books still remain off-limits.

The same daredevil spirit has informed many an apparently insane film or TV version over the past decade, which has seen adaptations of literary novels (Cloud Atlas, Life of Pi, Midnight's Children, Tristram Shandy) and epic fantasy works (The Lord of the Rings, A Song of Ice and Fire, AKA A Game of Thrones) that would previously have been written off as impossible. Vast classic novels or sequences – A la recherche du temps perdu (on French TV), Parade's End, Les Misérables – have all been ticked off.

With adapters no longer inhibited or intimidated, works totalling over 1,000 pages are tamed by gleefully drastic slashing and/or exploiting the ampler air-time available in TV series. CGI technology means that magical happenings, supernatural beings, wild creatures or crowd scenes have ceased to be either avoided or introduced nervously. Taboos - against adapting short story collections, or first-person novels, or multi-stranded narratives - have been defied.

With movies based on Stephen King's 1,300-page The Stand and Flann O'Brien's metafictional mind-bender At Swim-Two-Birds reportedly in the works, and Cormac McCarthy's peerlessly repulsive Child of God (with a moronic protagonist who combines serial killing with serial necrophilia) already shot by Franco, there's no sign of any let-up in filming the unfilmable. What should the buccaneering directors – who also include David Cronenberg, adapter of Burroughs, Ballard and DeLillo – be looking at next?

Subject to authorial permission, translating One Hundred Years of Solitude and Gravity's Rainbow to the screen must be tempting. Better special effects should also inspire another go at Moby-Dick (John Huston's 50s version is ruined by its rubber whale) and renewed efforts to subdue Don Quixote, which defeated Orson Welles and Terry Gilliam.

It seems unlikely, though, that these movie-makers will settle for the easy option of great novels still widely read, if largely by students; they think like mountaineers, determined to conquer unclimbed peaks just because they're there. For the boldest, the obvious contenders would include Joyce's Finnegans Wake, David Foster Wallace's Infinite Jest, William Gaddis's The Recognitions and Samuel Richardson's The History of Sir Charles Grandison (even longer than Clarissa, and much less happens). After Faulkner, Pynchon and Barth, anything more obviously film-friendly would be feebly retrograde.