Never,because bitcoin cash doesnt have any good position in the market,its purely a shitcoin which has a shit founder being a jackass all the time that is why most of the people wont try to opt-in this coin to repalce bitcoin's position,might be better if ethereum or neo would replace the king but not this bCash ? hell no !
Bitcoin is the pioneer of all cryptocurrencies. And for so, it is the market leader till now