I dont think a big industry or a size of super market is accepted crypto in mass adoption yet. I hope we will see something like this soon and will be using it for real purposes.
The only supermarket I know that's leading is Walt Mart but I don't have any news if they are going to adopt and accept bitcoin. It's going to happen and we'll see it that many supermarkets are going to accept bitcoin. Today they might not consider it as the population of bitcoin is still not that considerable for their business but once we've exploded up to 20%-50% of total world's population for sure there will be a consideration for those big leading supermarket or retailing companies.
Still since people will be paying in a physical shop more problems will probably rise e.g. fees and confirmation time, sufficient knowledge on staffs as bitcoin should be at least equally convenient as traditional payment systems so an increase of users may not be enough furthermore most governements are not in good terms with bitcoin but we'll see on the coming years as there will be changes although lets just hope it'll be good.
The confirmation time is a big concern for all the people and also to the supermarket companies that wants to try out bitcoin for their payment. The problem lies down to the network, they have to consider and see it first that there will be no troubles to face when they started to adopt bitcoin. But just like the way we transact, when we send bitcoins already to someone we have to wait for its confirmation and when it's recorded on the blockchain that's already good written there then that can be considered.