There is a possibility that all online gambling sites will be based on cryptocurrency in the future because day by day a lot of people in every country has recognized bitcoin and cryptocurrency, so cryptocurrency would increase its mass adoption that everyone will have their cryptocurrency and will be playing in an online crypto casino.
As long as many new gambling sites launch and promote the site on many websites, there is a chance for people out there to visit online crypto gambling. It will grow faster if in many countries legalize the crypto, so people will not be afraid to use crypto, even just playing gambling. If that happens, the mass adoption will not take too long, and we will see the crypto will get more popular among the people. But before that is happening, I think we can still introduce crypto to many people, but we don't have to force them to use crypto and let them decide by themselves.