In my opinion, we really need decentralized, self-hosted infrastructure.
I kind of hope we get a Fediverse alternative for WhatsApp.
I imagine running some kind of relay node on a raspberry pi, for perhaps 20-100 acquaintances. All traffic would be anonymized and encrypted as much as possible. Push notifications replaced by polling. Anonymous broadcast groups that allow anonymous sending and receiving of messages without revealing either who is sending or who is receiving.
Everything wiped every few minutes on the relay node.
Others would also run relays that are then federated together.
Thanks, never heard of SimpleX, but I will check it out.
But to make an analogy. Bitcoin wasn't good for privacy at first. But they added features and new coins like Monero were developed with strong privacy.
So I expect there will eventually be a private ActivityPub, either "on top of" or "next to" the current one.