One key reason we would rule out a refresh is that we, and our spy photographer, think it's too soon to be testing a midcycle refresh. The Camaro got a ground-up redesign just a year ago, so a refresh probably won't happen for a few more years. And there's a lot of camouflage here for something as simple as a styling update.
There are some details that indicate this Camaro is hiding some new performance bits. The front bumper has a prominent splitter, and the hood has a flap in it that could be hiding a window, or perhaps an extractor vent. Improved aero would be a natural addition to a track-focused Z/28 model.
We should also mention that at the ZL1 1LE launch event, Camaro engineer Al Oppenheiser said Chevrolet hadn't ruled out the possibility of a Z/28. The absence of a large rear wing like that of the ZL1 1LE is strange, but it's possible this car isn't testing aerodynamics, but rather a new powertrain.
One other point: Oppenheiser emphasized at the 1LE reveal that a key characteristic of the last Z/28 was its naturally aspirated engine. That leads us to believe any future model will also use a naturally aspirated V8. We've previously heard that GM has a double-overhead-cam V8 named LT5 in the works. It would have a 6.2-liter displacement like the pushrod V8s, but likely would make more than the current LT1's 455 horsepower. Car and Driver also says a Z/28 is coming with DOHC power, but it believes the engine line will have a displacement of 5.5 liters, a flat-plane crankshaft and aluminum construction.
If the Z/28 uses one of these engines, it seems a safe bet that it will first show up in a Corvette. The engine will probably appear first in a ZR1, which can trade on the history of the last DOHC ZR1 in the '90s, then the Camaro would follow. So don't expect to see a Z/28 for at least another year or two. This also touches on one more reason we think the Z/28 will have a DOHC engine: Having another model to put it in will help reduce the costs of developing this new engine.