Zelle is already owned by a consortium of banks. Even if FedNow were to make Zelle obsolete, it wouldn't do anything to harm the banks, so they ultimately wouldn't care.

Meanwhile, Venmo is owned by PayPal, who deserves to become obsolete, so we should all be cheering this on.

Not for Zelle/Venmo/etc.. Zelle is for P2P (person to person) and FedNow is for A2A (account to account). There are no take backs on FedNow so it's not intended to be used for P2P. No take backs means no recourse for fraud etc.. FedNow should supplant ACH waaaaaaaaaaaaaaay down the line.

What I have heard is that the banks that own Zelle will try to convert it into a directory service mapping identifiers like email addresses and mobile numbers to bank account information. The actual payment clearing will move off of Zelle, and all payment clearing and settlement will happen on FedNow or The Clearing House’s RTP system. That makes some sense to me.