I have to disagree at least for the case of Bitcoin even if it becomes a world reserve currency for governments, the majority of use will have to be off-chain. It cost me over a dollar to send any amount of Bitcoins. Steem/Hive have proven themselves to be very efficient, but we have also seen too much transparency. There is a culture of always using the same keys and never changing them. Then there is a problem of theft via hard-fork, which I think is possible in Bitcon but its harder to target individuals when most utxos are not known to whom they belong.