Think about it, it's a great opportunity as a filmmaker though. Give the Major a bunch of different "shells" to wear throughout the film; have Scarlett primarily play the role for star power, but have the character switch into other bodies played by different actors in the film: a Japanese body, an African body, a male body, a child's body, an old person's body. Film a scene with Scarlett acting out the part of the Major, then show the scene to the actor playing the "shell"; have them watch her take on the scene, and then film them incorporating her performance into their own: her delivery, her stance and movement, her mannerisms, her emotions, her facial quirks. Have Scarlett record all of the Major's dialogue for the film, then have the actor playing the "shell" listen to her performance to match her delivery and record their own lines, then use audio dubbing wizardry to blend and fuse the two tracks together, creating a voice that's Scarlett and yet not. The goal would be to use all of these actor's individual performances to create one complete, composite performance and have it come across as totally natural and believably one character.