You should consider adding Bitcoin Cash to your site. Perhaps you could let people invest their bankroll as well? Everyone is looking for returns
I think they will never consider to add BCH on the site, as we all know Primedice does not support BCH and since stake is the brother/sister of primedice then I'm sure that they will stick to their decision to not support BCH.
We have still time to even consider adding BCH, there is now way to tell how this altcoin will shape in the future.
Moreover, I heard that the network supporting BCH is painfully slow and services accepting this coin might require even 20 confirmations.
Which is roughly more than 10 hours of waiting before your tx will be properly listed.