It is pointed out that AMD Radeon HD 7990 GPU which featured dual GPU core based on Tahiti, when it was just released in April 2013. The card used dual GPU Tahiti XT2 core with 950MHz base clock with 6Gbps memory bandwidth with 2x 384-bit memory interface and 3GB GDDR5 memory.
But considering the issue this multi-GPU R7XXX series faced with micro stuttering, it was inevitable that flagship would be taken down eventually.
The stocks of the HD 7990 were also very limited, and it was just a matter of time that the remaining card stock would simply be over. It also should be noted that the price had a very high price tag which then met Nvidia GTX Titan.
AMD Radeon HD 7990 most likely is the most short lived flagship GPU card- period!