Relays are going to be very key to this network. F2P isn't going to deliver the best UX.
Paying for a couple of very good, low latency and well-connected relays will be necessary for a good user experience. Hopefully this creates a competitive market for relay operators. Relays will offer additional features that we demand.
There'll be pushback on the notion of paying, but then again if it's free then you're the product. And the whole point of nostr is to avoid that!