Generally speaking, when you are seeing accessories for an as-yet-unannounced product on sale, you can count on seeing that product make its debut fairly soon.
Of course, we could also see these offerings disappear too, the result of a mistaken click of the webmaster or merchant getting set up for a future roll out.
The images from the merchant’s accessory offering (which by the way is not a terrible deal from the looks of it) have taken a Nokia Lumia 920 and placed it within a rendering of their hard cover case. We know this because the back of the device shows the 920’s double-LED flash while the cut-out shows ample room for something more (like a xenon flash).
The cutout for the speaker is present as well, and the rest looks like standard fare for a Nokia design, volume, power/lock and camera buttons along the right side of the device and there it is. This certainly not spoof of some kind as the vendor has a solid rating and thousands of reviews on Amazon.
If you are planning on picking up a Nokia Lumia 928 whenever it becomes available, and counting on Verizon or Nokia to actually announce the device, this could be an opportunity to get some handy accessories for it.