In China, Use of cash is beginning to decline as ALIPAY and Wechat become more wide spread among stores , restaurants and websites. For me , only use coins now is to give to beggars. and maybe soon, as smartphone prices fall further, they too will accept donations in ALIPAY and Wechat
Governments also beginning to discourage the use of cash
Outside of China, I see Bitcoin or another crytocurrency will do the function of ALIPAY and Wechat. One we use pay for good and services online and IRL. One we transfer money to one another and one we hoard when going get going get tough
Will Bitcoin replace cash ?