Of course there is demand, without doubts, some people even deposit on bitcoin casinos, exchange coins and then withdraw (which is against laws). There are comments like you need offshore companies and so on, there is no need of company, you can do it like mixers exist. Gain of trustworthy is most difficult task but that's your problem. Also there are some good non KYC similar services so what about to offer something different? For example exchange tokens of some ICOs in btc if user wants to get invested money back but can't because coin isn't exchangeable at the moment?