It will never happen, most people continue to use government currency and it will stay like that. Crypto will always be a minority. I think people become too blinded by what average people do when they spend time on a niche forum like this one.
Yeah, you are right. Maybe cryptocurrency will be a new option in the gambling games for the transaction besides of fiat because people only know fiat to gamble. But soon, after people know about cryptocurrency, I think they will choose to use cryptocurrency because with cryptocurrency, they can hide their identity and they don't have to send any document to the gambling site.