No doubt that BTC would really be mainly used since this is the main crypto as we all know which every online gambling site would definitely have this option anytime to make it as you main deposit option
Recognition of other altcoins would entirely depending on the house if they do saw that theres a public request on adding it up then they might consider it.
No doubt about bitcoin that is the cryptocurrency that everyone wants to engage in gambling. I don't want to choose any other crypto in gambling though the value went lower today but its going to be huge someday that these casino's will be more popular as it is today. There will be some altcoins that will be recognized and others would love to engage with but it will be very few.
I would not play with crypto because I know its worth in future would be a lot more than what it is today. So if I have to play it would be with money because its value would be decreasing in years and even I lose it would be money and not crypto.