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?
For me, no. Even how far crypto have reach, there are still people who prefer fiat over crypto. Some may give it a try but pretty sure some site will maintain that only fiat is allowed to used. I don't see anything wrong about it and we can't force someone to like crypto simply because it's their own preference. What's posssible is lot of crypto based gambing site will be created as time pass by because of how convenient and profitable it is.