What do you think will be the next option for Bitcoin mixers, is it no KYC casino or Monero?
I don't think so that what mixer's are actually does that the non-KYC casinos can do.Because the purpose of the two is different, Mixer works to strengthen privacy by making it hard to track transactions, while non-KYC casinos protect privacy but its main purpose is to allow gamblers to hide their identity and gamble freely.
In this case, what you can do for only privacy maintaining without doing gamble-
You can also be converting bitcoin to monero and back to bitcoin on decentralized exchanges.