It might be far-fetched, but it fits any
real paranoiac's theory *shifty eyes*. Subaru needed DI tech and now they have a new platform as well. Rumors of a turbocharged FA have been verified by Subaru, but not in the BRZ. As WRX/STI model line diverges from the Impreza, it would only make sense for it to get the newest tech. As far as Celica/Supra: I can't imagine the whole badge engineering twin-models thing going for very long. After this car, I imagine both companies will use the platform for what they want to, separate of each other.
Sorry for the
guys.