I think FedNow impact on debit will be missed. Cost and speed are only 2 parts of the problem to solve. The debit card instrument is still a materially better interface/experience than the account + routing number instrument; people have a debit card on them most of the time, you can swipe it in places etc. Without changing the UX of fednow, hard to imagine it competes.

I think fednow probably cannibalizes a bunch of ACH (because its same UX but faster) and a bunch of wires (bc its the same speed but cheaper) but less debit.