I'm almost positive that the Brera and crossfire are not related at all. first of all, concepts of them came out seperately and about the same time. second of all the Brera was designed be Giugiaro and the Crossfire by Chrysler. also they don't look anything alike. Also the drivetrains are completely different, and i don't know of any connection between Alfa Romeo and Mercedes or Chrysler. The crossfire is essentially a MB car with some Chrysler flair added on top.
I don't think Subaru could afford putting a $33k cars drivetrain in what was a $35k cars interior, with both attributes being the more expensive part of the car, and sell it for $25K...
but if they do, I'd sure as hell buy one