A $100k Supra? Toyota may be pushing its luck. The Z7 is expected to come in at the $120k range which is fine for a mid-engine BMW sports car. The only problem then is that will people pay for a BMW sharing its platform with a Toyota? That certainly takes away a bit of the roundel luster that BMW banks on these days.
Power is expected to come from a turbocharged inline-6. The most likely candidate is the S55 3.0 liter direct injected and turbocharged inline-6 used in the M3/M4. It will be supplemented by an electric drivetrain producing somewhere over 100 horsepower. Combine that with 425+ horsepower from the turbo six and you have a recipe for a car around the 550 horsepower range. In other words, what the i8 should be.
Why would anyone want the i8 if for less money you can get a mid-engine hybrid offering higher end performance? That is a pretty big issue and there are several other questions about the market for a $100k Toyota Supra. A lot can change by the time any official word comes on this project if it even exists. CAR seems to be guessing as CAR often does.