No word yet as to why Downey backed away, but he recently quit another major film role, dropping out of the sci-fi movie Gravity which is also set to star Sandra Bullock. George Clooney is taking his spot in that film.

Oz: The Great and Powerful is hoping to begin production later this year from a script rewrite by Rabbit Hole's David Lindsay-Abaire. The film's story, which is said to be a prequel to The Wizard of Oz, introduces us to the wacky wizard as a circus wrangler transplanted to Oz by yet another tornado.

UPDATE: THR is now reporting that Johnny Depp has stepped away from the project. Has this guy ever stepped away from anything? No word on why the most prolific actor in Hollywood isn't up for the role, but some are speculating that it may be something as simple as not being able to work it into his busy schedule. Perhaps he wasn't able to work around his Lone Ranger schedule? Regardless, James Franco is now said to be next in line for the role. Things are moving quickly on this one, so expect a yea or nay soon from the 127 Hours star. Producer Joe Roth is hoping to start production in the second half of this year.