There was a 12-hour backlog on ETH today, so I don't see it being any more usable as a currency than BTC. And it's not even intended as a currency, just as fuel for ETH blockchain dapps. Maybe segwit will help BTC perform as a common currency, maybe not.
In the future, most micropayments will be probably made by another altcoin we've not seen yet, while BTC will be the gold people keep in a safe for retirement. Right now we're in the wild west where people still trade in gold coins, but mass adoption could reveal how cumbersome that is.