Will FedNow be mandatory?

I've been following the news about the Federal Reserve's new real-time payments system, FedNow, and I'm curious about its implementation. My question is, will FedNow be mandatory for financial institutions to participate in? Will it replace existing payment systems, or will it coexist with them? Will there be any incentives or penalties for banks that choose not to adopt FedNow? I'm interested in understanding the potential impact this system could have on the financial landscape and how it might affect the way consumers and businesses conduct transactions.