Wicked IS FINALLY coming to the big screen! Who will play those witches?

There has been talk swirling around about the mega hit musical Wicked being adapted for the big screen for years. In fact I read somewhere (I honestly forget where!) that producer Mark Platt wanted to adapt Gregory Maguire's best selling novel as a film initially, but produced the stage version first due to lack of investor interest.
Well, now, according to the news out of Comic-Con, not only is Universal doing it (Platt has a deal there) but after looking at various directors, including J.J. Abrams, Rob Marshall, James Mangold and Glee creator, Ryan Murphey,are now courting Stephen Daldry (Billy Elliot, The Reader, The Hours, Extremely Loud and Incrediby Close) to direct.
Platt, by the way, is the producer behind the Gosling movie Drive which my hubby, Mark worked on.  I would love it if he could work on Wicked too!

Okay, guys, who should play Glinda and Elphaba?