US same-day ACH

In the US, the new NACHA same-day ACH will have a 5.2 cent per transaction fee that is paid by the originating institution to the receiving institution. It is up to the institutions whether they charge customers anything for it. But even if they were to pass that whole cost on to merchants, my guess is that the merchants will prefer the low-cost, same-day payment over the existing schemes (e.g., debit cards).