The super duper Mustangs might not cause a spike in sales. But what it does do is generate buzz. Case in point, this an F-body board and its generating buzz, imagine what it will do on a mustang board?
Second, the factory effort will mean lots of the those parts will probably be available and will bolt onto the street cars. More buzz, more support from the aftermarket, the dealers. Anyone remember Downs Ford? They sold more 5.0/Fox body performance parts than probably anyone else on the East coast or so it seemed. I can't name a Chevy dealership that was on par in that era? There is the NMRA. But no NCRA? I'm thinking the Mustang benefits hugely from having an entire race series named after it. Camaro, no such luck.
The Z28 might be coming back, but as what? A 3800lb slug marketing tool? Or a 3200lb performer worthy of the name? GM can't really do the latter, because if the Z28 were a full on effort, it might step on the Vette's toes, that ain't gonna happen. I can hear the crying from the Vette crowd already. If GM really want to

Ford and

the Mustang, they could put together an F-body that would absolutely embarrass the automotive world on a performance versus dollar basis.
Chuck the full-on Z06 (not the supercharged ZR1, that's reserved for the Vette/CTS-V crowd) powerplant into a base optioned 5th gen with factory installed headers/performance exhaust. No power seats, no cruise control, reduce the sound deadening material by 50%, no super duper stereo with 18 speakers and amps, cloth seats, performance shifter, smaller lighter more reasonable wheel/tire combo with a performance spring/shock/sway bar package and I bet it stands with the best of them, so much so that base corvette guys would be
And call it the Z28, bring its curbweight in at 32-3300lbs (by whatever means necessary) packed full of 505hp.....Hell you could even keep the AC, the PW, PDL. Think FRC Vette meets 5th gen Camaro......
Oh and keep the price at $32k+/-
GM will never do it....I hope they make a liar out of me.