Nobody will pay a coffee with BTC, just like you don't pay for your stuff with a gold coins.
Some say Litecoin will be used for that but I doubt it. Coins like Cardano or IOTA will be used for transactions. I'm not sure about Cardano but with IOTA you can transfer a fraction of a cent (or no value at all) without fees (that doesn't mean everything will be always fee-less).
