It's quite possible Scion is saving the iR for the show's closing weekend (this weekend), we'll just have to wait till then.
For now, I heard it was to be based off the Aygo. If true, comparing the teaser in the link you provided to the current Euro Aygo design, we'll be getting something designed specifically for the North American market....as far as the rear end goes:
For now, I heard it was to be based off the Aygo. If true, comparing the teaser in the link you provided to the current Euro Aygo design, we'll be getting something designed specifically for the North American market....as far as the rear end goes:

