Agreed - the capabilities of a specific mining gpu must outweigh the lost scrap value since one cannot sell it on to the gaming or visualisation markets
Until that time, gaming cards will be the card of choice I believe simply due to their scrap value being taken into account when calculating lifetime ROI
Perhaps another point to add that would be desirable: compact size. The smaller the card the smaller the rig and the smaller the rig the more rigs one can fit into the space - thereby reducing the space a farm takes up (heat dissipation of course would need to remain unaffected.......)
The new mining specific GPUs are said to be 2x faster in mining for ethereum almost 60 MH/s for $350
https://hothardware.com/news/nvidia-allegedly-readying-pascal-crypto-mining-gpus-ethereum-bitcoin