And apparently it is happening in August already. Chinese VR Zone posted that AMD’s upcoming Tonga GPU will arrive sometime this August in order replace the GPU you guys all know as Tahiti PRO, which is the R9 280 GPU located in the mid-end range. Little is officially known about long rumored Tonga, but the GPU should be locked and loaded with a 256bit interface that has 32 CUs and 2048 Shader processors. Next to that it should get 32 ROPs and 128 Texture memory units. 

Tonga might be based on GCN 2.0. The card would become available with a memory capacity of 2 GB and perhaps we'll see some 4 GB variants. The Tonga graphics architecture will be built on the 28nm node from Global Foundries and would feature a new design scheme introducing latest architectural improvements such as new ACE (Asynchronous Compute Engine) Units and more focus towards compute shaders. The main focus of the Tonga GPU is said to be the power efficiency. Tonga will keep the basic technologies of the Radeon lineup such as Mantle, TrueAudio and XDMA for CrossFire support. 

AMD Tonga GPU to replace Radeon R9 280