I don't think you can replace Fiat currency since many peeps still used that, but there's also a chance for Bitcoin to be used as a payment method, but considering the high price of Bitcoin makes you think twice before even use Bitcoin. Cheers!
The high price of Bitcoin, I don't think, will be a big problem if Bitcoin wants to be applied to a special payment method, because digital payment methods will only be an additional option for those who don't often carry cash in their pockets.