This question is similar to "will bitcoin/crypto replace fiat in the future?" which has been discussed many times in the Bitcoin Discussion board. I have to say that crypto will never replace fiat in any type of business including gambling business. Fiat gambling business will not change to Crypto gambling business, fiat gambling may start to use crypto as an alternative payment method but fiat will be still be the main currency.
I know some people are so sure to see that there will be a time when all business are cryptocurrency based but I cant fully agree with it because I believe that fiat and crypto are not replaceable to each other.
This reasoning is very similar to when people discussed the possibility of replacing horses with cars. For thousands of years, people rode horses; no one could believe that they would ever be replaced with iron things. However, as it turned out, people preferred a more technological, faster, more convenient form of transport. Sounds familiar?
The same thing will happen with the fiat horse, it will be replaced with cryptocurrency, cryptocurrency is a computer technology car. Perhaps I argue as a crypto enthusiast, but enthusiasm helps a lot to progress.