Think of it more as an alternative method to fulfill the kinds of things that ACH and Wire Transfers are used for. You'll probably never see 'this is a fednow function' on any consumer facing documentation, but billpay, payroll etc will use it.
I'm assuming that banks and payment services will add it to their services. Everything that goes over ACH will gradually switch to FedNow. There will be no noticeable difference to users except that transfer will be instantaneous instead of taking days.
