Anonymity and popularity of Cryptocurrency are two of it's the best attraction.
And Cryptocurrency games are more transparent.
Will, there comes a time that all online gambling sites will be Cryptocurrency based?
It is possible, if most of online transaction are regulated by cryptocurrency however, this will take time to happen though. The fact that anonymity gives more advantages and favorable to the users since their transaction cannot be tracked down so their identity is away from the sight of public. However, their users will be limited only to crypto users so I think it is still better if there will be some online gambling will accept fiat as a bet.