To my understanding, this was the dilemma Ford had all along with giving the Mustang an Independent Rear Suspension. While it would obviously give the Mustang performance advantages in handling, because of what was involved, it would increase the weight significantly, as well...
I hope you're right. The flat plane in the GT350 is a truly amazing engine. But I'd dare say you're forgetting about the pressure by the Prius-Nazi crowd is putting on regs.
I'm not an engineer, but, I'm not sure that a smaller turbocharged V8 would be practical. More cylinders equals longer...
I honestly believe this is a VERY good possibility. I think the upcoming turbocharged V-(SIX) Ford GT, is a "tell" to Ford's plans for the Mustang. Given CAFE regs, Obama's plans for increased fuel economy, etc. It all points towards "Ecoboost" 4 and 6 cylinder only Mustangs. Covet your V8...