I think the process of achieving acceptance of cryptocurrencies solely depends on the government. If they see that cryptocurrencies are a threat to the economy or to the country, then this would affect its overall acceptance. This also applies to physical casinos in accepting cryptocurrencies as a payment.
Like what you have mentioned, lots of online gambling websites require KYC documents due to stringent regulations imposed by their respective government. Since online gambling websites can easily get away due to their nature, physical casinos, on the other hand, have much further stringent rules- that is why we won't see physical casinos accepting cryptocurrencies in the near future.