In the next 10 years I believe that most casinos will end up being non-smoking venues. It will eventually happen. Right now casinos have gone non smoking are seeing the same number of people and they staff for that amount of people, but are not seeing the volume of play, since smokers have to now go outside to pursue their habit. Casinos will eventually adjust to handle the difference.
In Iowa where I work, there is a smoking ban in public places, but the casino floors were exempted. I would guess that this will last a couple of years and casino floors will lose their exemption because of backlash from other businesses and the public attitude towards smoking.