Who knows? Your statements could become complete true over the time because cryptocurrencies are having all the potential to make it possible. At the same time gambling houses are working with all their efforts to get what exactly gamblers are preferring; it means when gamblers are comfortable with fiat gambling then they will do anything to make it available for those gamblers.

In some sense until gambler's will not be demanding about fiat based the gambling, I guess we're not going to have all gambling houses will be having only cryptocurrencies. When there are gamblers who are preferring fiats based gambling, then such gambling will continue to exist regardless of how crypto based a gamblers are dominating in industry. In many discussions, this community has concluded about fiat will never get disappeared from this world just because of cryptocurrencies.

When fiat currencies will be staying with us, then definitely there will be some fiat based a gamblers as well which makes there will be less possibilities for having all the gambling houses to be cryptocurrencies only based.