The last time Guillermo del Toro agreed to work with another big filmmaker, we never quite got to see his vision for The Hobbit. Hopes are higher for a new potential collaboration, as he's in talks to develop and direct Fantastic Voyage for James Cameron.
Avatar's overlord has been trying to get a new take on the miniaturization sci-fi adventure afloat as a producer for years now, burning through such name directors as Roland Emmerich, Shawn Levy and, though he was only considering the job, Paul Greengrass. The project currently has a script by Justin Rhodes based on David Goyer's treatment. According to The Hollywood Reporter, they would both stay aboard to work with GDT if he does officially take the job.
Cameron has had dreams of a big blockbuster version of the story for ages, which in the 1966 original finds a team of scientists shrunk to atomic size and injected with a miniature submarine into the body of a scientist whose life is under threat. It sounds like a fun project for del Toro to work on while Pacific Rim's sequel cools its Jaeger heels in development hell. Just picture freakish internal chunks of the body brought to life by an art and effects team under guidance of the man who made Pan's Labyrinth, Blade II (written by Goyer) and, most recently, Crimson Peak...
We'll have to wait and see if he takes the gig, especially given that he has plenty of other projects under consideration.