Repair-It

A $75k Camaro can tackle a GT-R, or at least run with it. A C7 Z06 for similar money will really do a number. The GT-R is such a high performer that I don't think it's reasonable to expect a GN (which should sell for $45k or so) to have that level of performance. The bar has moved, and the GN existed in an era where performance was not the focus for everything except very exotic stuff. And that exotic stuff required huge compromises.

Today, performance is there in even mundane stuff. The GN took technology which was right on the fringes and threw it all at a sedate G-body. That was cool. But what technology is there today that you could repeat that? The 3.6L TT does have all that stuff, but it's not a differentiator in 2014 (except that it does have leading output for a V6 in anything but a GT-R). If it came out 7-10 years ago, that would have been different. They kind of lost the window to repeat the conditions, which is what I keep saying.

Also don't forget that in the 80s, they were so excited to have a non-sucky powertrain that they totally glossed over the lame handling and braking the GN had. Today, it's about the whole package. And something like a GT-R is going to require at least a $75k car to match. If you want to focus more on acceleration, Chrysler already has the Hellcat, but I don't think a GM Hellcat product is very interesting. Aside from that, are you proposing that the GN be the Hellcat-type product for GM?

The GN's handling and braking are lame by today's standards, but were pretty impressive in the 80s. Especially the GNX with its fancy rear suspension and aluminum brake drums.

There was nothing from any manufacturer in that body style (GT tank?) that could touch it. It would even outperform the NASCAR special, aka the Monte SS. Chrysler was busy making mediocre FWD cars. Ford had the turbo coupe Thunderbird, but that didn't quite have the power or the driving dynamics (although you could get a manual trans). The V8 versions of the T-Bird and the Cougar were even less exciting. The BMW 635i would probably out drive a GN, but the US never got the good engine. Also I'm pretty sure the 635i would have cost twice as much as the Buick, FWIW.

I will also point out that the biggest GM division difference between the 80's and now is in the 80's Cadillac did not make performance vehicles.

Ok,
A few very good points were made:
Cadillac didn't make performance cars - valid point. This changes the dynamics of the internal competition a little.

The way I see it, The Camaro is supposed to compete with the Mustang and the Challenger/Charger, including the Hellcat and GT 350/500. - Make them GM. They could have the ZL-1 next gen compete with the Hellcats because it doesn't have a real purpose otherwise and is already supercharged. The Z-28 is the track car. SS could be entry 8 cyl, and maybe bring back the IROC to battle the Scat Pack and BOSS track packs instead of the option package 1LE.

The Buick can still go after Asian 6 cyl turbo - GT-R, if Toyota brings anything back, the NSX when Acura brings that back. (Buick is huge in Asia so this makes sense)
The Caddy can go after the Germans - Audi, BMW, Porsche. - They have kind of already targeted them.

Next point:
"A $75k Camaro can tackle a GT-R, or at least run with it. A C7 Z06 for similar money will really do a number. The GT-R is such a high performer that I don't think it's reasonable to expect a GN (which should sell for $45k or so)"

It is reasonable. A quick calculation at http://www.dollartimes.com/calculators/inflation.htm shows inflation of the GNX price tag from $29,900 in 1987:
$29,900.00 in 1987 had the same buying power as $63,060.32 in 2014.
So, the GNX could be 63K, which gives Buick a lot of spending power to make this awesome. Remember, the ZL-1 Camaro is 55K.

Sure, the GN price adjusted is:
$19,000.00 in 1987 had the same buying power as $40,071.77 in 2014.

So put a sick 500 HP TT drive train in the GN, and for the GNX for an extra 25K add magna ride, 100HP boost, stickier tires, and get that GT-R!!! (and NSX!!! Supra???)