If bitcoin has gotten mass adoption, and less suppose it has in 20 years, then i think many shops will accept bitcoin, with that in mind, i think most services which require fiat will have an option to buy with bitcoin, Like we are seeing now with creditcard. Because in 20 years the mobile phone wallets, should be more advanced as credit card systems today.
If mobile phone wallet reached to every person and the shops started to accept bitcoin then I think at that time there will be more than 80% people who will prefer bitcoin as their payment for their purchases etc.