It looks like AMD will drop using the Radeon HD 8000 naming completely, in fact according to something that VR-Zone noted there might be another change. It seems that AMD will use a different naming aka Radeon R9-XXXX. So the big daddy flagship would be called R9-9970 and say the flagship dual-GPU board R9-9990.
This naming scheme will correspond to the current APU segment where you can find for instance A8 or A10. It is unknown at this moment if AMD will move on with the R9-9000 system as if they continued with the current x000 system or if they rewind the numbering.
According to this information AMD's Radeon HD 9000 series, as it was often called in the last days, will get a new name, which is very similar to the name of the current APUs. According to a report on vr-zone.com these name labels should be applied to desktop graphics cards too. This one is not quite sure because the way it looks currently, the U.S. American graphics card manufacturer has two different options. Being safe is, the "R" prefix, which could be a reference to the respective generation or to the power class either.
If the first digit after the new "R" prefix indicate the particular generation, then a Radeon HD 9970 will be a R9-9970 and a Radeon HD 9870 from a R9-9870th The latest generation, however, would listen to R7-7970 (Radeon HD 7970).
Obvious is, however, a reference to the naming scheme of current APU models. Here AMD is sorting its chips after the respective class, while the subsequent digits make the classification within this class. To cite a few examples: AMD A10-6800K is the current flagship of the "Richland" APUs, followed by a further high-end model A10-6700. The mid-range models are named A8, such as the A8-6600K and A8-6500. Looking on the graphics cards this means that the next flagship graphics card will come as R9-?970, followed by the R8-?870 on the market. The first number that we have provided here with a question mark, it is still open.
Specifically could look like this:
Radeon 9970 -> R9 Radeon-xxxx -> R9-(i)970 followed by R9-970 (i +1) 970
Radeon 9870 -> R8 Radeon-xxxx -> R8-(i)980 followed by R9-870 (i +1) 870