I'm sure they will gladly take your cash. Also remember that we in certain geographic areas already had (still have?) gaming where cash was not used, as in many of the casinos, both native and civilian, in the Midwest, when they first allowed them, were tokens/chips only and the machines did not accept US coins/bills. You took a trip to the cage and exchanged real money for tokens and vice-versa. Some of them (Kansas City for a while) could only give you so much in chips/tokens each day.