The only fix to this is to replace phone numbers by secret 256 bit keys that are never reused...

Never gonna happen.

WhatsApp has avoided the pressure of E2EE backdoors and whatever politics because they were never needed.

1. They collect all the metadata in unencrypted format and link it to phone numbers, making a huge social graph.

2. Backups are not encrypted by default and enabling of them is pushed. So the messages were never actually encrypted for most people and police can get messages without the actual phone.

3. iCloud E2EE backup fight in UK was mostly because of 2. as people started to opt-in for encryption.

Phone numbers were never supposed to be secret.

Nor were social security numbers.

That’s not gonna happen because the whole idea is to link your real identity to the digital one, which is why you should never trust any company that refuses to give you an alternative option to the phone number.