I don't think bitcoin will ever get to mass adoption for everyday payments. My gut feeling tells me that this is more of a behavioral challenge on the part of the consumer and merchant, than a technical challenge of a merchant accepting bitcoin payments (I guess there are already many online outlets doing so, and in Amsterdam plenty of brick&mortar places accept bitcoin to buy say a pizza or a coke). For the average consumer it might be tricky to get the notion of how much they are paying, they would probably calculate back to a currency they're familiar with. E.g. the consumer needs some kind of anchor in their minds to determine the amount of value they are parting with in exchange for whatever product or service they are buying. Bitcoin being so volatile and high value per single unit doesn't really help (say you end up having to pay someone 0.008 bitcoin now, and 0.009 bitcoin in 15 minutes, that doesn't make it easy for most small payments)
The following is purely anecdotal, but I actually know quite a number of people, and not just pensioners, in Netherlands and other European countries, who still calculate back to their original pre-euro currency when paying something in euros. Mind you, the euro was introduced over 14 years ago! So, I guess it takes some time for the wider population of consumers to get comfortable with a new currency (whether physical or crypto). A solution could be to have the underlying payments infrastructure running on some kind of cryptocurrency/blockchain to keep costs low, while simultaneously providing the end users an easy unit of value (and of account, not unimportant for the merchants when they're balancing their books!). Put it in another way. when I transfer money to someone else's bank account, I don't really care about SWIFT, SEPA, IBAN or whatever mechanism there is that ensures that my money arrives safely. I'm just concerned that the amount I send also ends up on the other end, as fast as possible at the lowest possible cost, regardless of what happens under the bonnet.