Cash is king, but only hard core's carry tons of cash now. Even 15 yrs ago, most people got paid on Friday's and "cashed" their checks. They came into the pool room with money in their pockets, and had some disposable cash. Those days are long, long, long gone. I could see paying phone to phone with Venmo or Paypal or apple pay etc, could work well with the way people "carry" money today.
The only time I think it would cause a problem is "big" action, for 1k or more. All the electronic pay systems have some sort of limits imposed on them.