That's why I said "as we know it." The current implementation is not viable, and the blockchain itself is a huge problem. Literally a huge problem. It contains all transactions that were ever made with Bitcoin. And you are supposed to carry it on your smartphone! Truth be told, the blockchain can be trimmed; but that was never done. It would break a whole lot of proofs of correctness of early transactions in the remaining segment.
However it is refined, the blockchain concept is the Skynet of currency. It WILL not go away, imho.
It's a curious idea, I don't deny that. However it is an overkill for cash. There is no practical reason to have a formal proof of payment when you pay $1 for a can of soda, but there may be such a reason when you transfer $10M BTC for a pro athlete. In real life we do exactly that - we pay with pieces of paper that are rarely looked at closely because the risk of counterfeit is low. At the same time when a team pays another team no money is even sent; what is sent is orders to the bank - and then banks sort it out amongst themselves.
The problem of the blockchain is serious enough to prevent placing BTC into chips of cards. I think it is safe to say today that nothing larger than a card will be accepted by the people - simply because the cards work great already. Cards with chips are pretty much unhackable. But BTC not only requires some serious computing power at every client, it also requires some serious storage and a network link. In other words, good luck going for 30 miles to the farmer to buy some produce. You won't reach the network there, and you won't be able to pay on the spot. But you can do that with a card because, at least, the card itself is an ID. And certainly you can pay with paper bills.
I cannot say right now how the BTC would have to change to support future transactions. However I think the concept of digital cash will remain low priority for many people, and banks will continue to hold people's money for them. The reason for that is very simple: your savings are safer in the bank. Digital cash in your phone can be easily lost, unless you are paranoid about backups. And there is yet another problem: backups can be attacked by thieves just as well as the primary wallet. BTC has to change to even become usable, that much is obvious.
You'll get your government-assigned piece of that big server in the sky, and you'll be connected through (today) your smartphone and (someday soon) by a tidy little biomechanical interface.
And your kids kids will have their brains doing a lot of that process without being conscious of it and perhaps even without willing it