This approach doesn’t change the current model at all, it only moves part of the client’s workload onto a specialized relay.

For example, if someone follows too many users and the outbox model becomes painful for them, they can run a local relay that automatically pulls events from their followings’ write relays. Then they just browse that relay with Jumble. This is actually a feature I’ve wanted to add to nostr-relay-tray for a long time, but have kept putting off. And of course, if they don’t want to run a local relay themselves, they can wait for a paid service to offer it.

If someone doesn’t follow many users, or mostly browses relays directly, then they don’t need to do anything, they’re already perfectly happy with the outbox model.