Maybe they can replace her with Cheryl Cole... and then replace Cheryl with Nicole Scherzinger for the American leg
Honestly, I wouldn't mind seeing the Spice Girls without Posh. There's nothing about her that I really find essential to my conception of the group: Mel B has the attitude, Baby has the girl-next-door look, Mel C has the vocal chops, and Geri has the Union Jack dress. Sure, Victoria did give me those "stuck up bitch" teas, but I can live without them.

(And mind you, I'm not saying that that's what she's like in real life.)