This all assumes the Ethereum Foundation won't just modify ethash to be resistant. They might be able to do that even if bitmain is just stacking gpu's. It's never a done deal. Cryptos are evolving systems. I'd love to watch bitmain ship a few thousand only to have ethash modified in a way that no firmware update could fix. 1gb ram per gpu might be an easy target since gpu's used now have at least 4gb. Just quadrupling the ram usage might render their asic worthless and keep eth distributed.