I can't confirm or deny this myself, but there are indications from the graphics card channel at the moment that Nvidia is not naming the upcoming Maxwell GeForce graphics card series in the high-end space a GeForce GTX 870 and 880.
The latest rumor (and it really is a rumor) is that November the 9th Nvidia will announce its new Maxwell GPU architecture. And then just over a week later on September the 19th it will announce two graphics cards. Now the names of the products would be GeForce GTX 970 and 980.
The GeForce GTX 970 and GTX 980 will be based on NVIDIA's GM204 GPU as stated, based on Maxwell GPU architecture.
