Yes, it's very hard. They would have to completely re-architecture their systems. For e-commerce, the client can sign his or her address with the shipper's pub

Yes, it's very hard. They would have to completely re-architecture their systems. For e-commerce, the client can sign his or her address with the shipper's public key, so that only the shipper and the recipient are guaranteed to know the address. To the user, this could happen transparently without any change in UX, where the e-commerce website acts like a keyserver. For email addresses, phone numbers, names, etc. it is more difficult. You can't just store a hash of the email address if you want to ever be able to email your customers. Internal documents can be more trivially end-to-end encrypted. Imagine the whole company shares a WhatsApp group chat. Nobody has to ever hold a plaintext copy of an internal document. Only permit access on company devices which hold the keys in hardware.