I seriously don't think they would make the Impreza BIGGER than the Legacy!
The B11S design was in the spirit of the SVX, a large Grand Touring sedan.
It's definitely not Impreza sized, and it was designed before Zapatinas came to Subaru, so it couldn't possibly be the look of the next Impreza.
The B11S was a prototype made in '03, along with the Scrambler.