Shop I work in, we don't get many cash sales. Perhaps two or three a week. I think people still like to give cash for birthdays and the like, and of course there are those that trade mostly in it, so we still keep a float. Essential if we have to give refunds things that were bought with cash. And also for any of our petty cash (mostly postage costs and the window cleaner) needs.
Personally I always keep about £10 on me, usually in case I want an drink or ice cream when I'm out running. The plastic notes are brilliant. I no longer have to worry I'll find a soggy mess in the laundry if I forget to check my pockets!
So while the majority of people use cards or their phones/watches to pay contactlessly, I can't see cash disappearing completely any time soon.