I agree with Mike that if they were going to make the teams spend money on a new car anyway, why not FIA GT3 where the homologation is already set? All they would have to do is maybe slow the cars down a bit with an intake restrictor and rock hard tires.
He also mention FIA GT3 cars look cooler, I agree -
911 America (991)
The Euro spec GT3 997
Since Porsche is a valued partner of both series before they merged, it shouldn't shocking what has transpired.
So we have clipped Grand Am Spec GT3 cars to look forward too and half the field being Porsche Americans, fantastic! (Sarcasm).
This month's test at Daytona should be very interesting....
In the meantime you got Pirelli World Challenge to look forward too which will feature FIA GT3 cars next year including the current FIA GT3 Porsche GT3-R and likely the future 991 based car.
PWC recently announced a new Pro-Am subclass in GT as its expected that factory involvement will get a major boost next season.
If you really wanna see FIA GT3 cars in America, pay attention to the Pirelli World Challenge Championship.