I think GM is still too consumed with their focus group studies and trying to make every car in their entire corporation appeal to every human being on earth to make anything unique, attractive, and appealing outside of Cadillac. And the GTO don't count.
Chevy is about as bread and butter as it gets. With the absence of the Camaro, they have nothing other than the Corvette to get people's attention.
Hell, as much as it pains me to say (and you all know by now Ford has been on my s--t list forever), Ford took the Mustang from the 1970's to the 21st century in one year. And they didn't even have to, since they pretty much own that segment of the market now. And guess what, it's still affordable for your average Joe..... something the GTO isn't anyway.