From Spiderman to the Wizard

Today, Sam Raimi was signed on to direct the "Wizard of Oz" prequel, according to Deadline Hollywood. From what I remember, in the original novel, and in Wicked, the wizard was a man from some place like Kansas, who got him his balloon caught in a tornado. The circus performer landed himself in Oz, where he somehow gained a stronghold and became the wizard, benevolent to some, dictatorial to others.

I wonder how the movie will address the wizard once he gets to Oz. Will he be the benevolent leader seen in the movie? Or the evil, manipulative despot of Wicked? Will Robert Downey Jr. star? I can't wait!