They probably can already do everything you say, eg: cross reference and internally "trade" (meta)data between facebook, instagram and whatsapp backends and del

They probably can already do everything you say, eg: cross reference and internally "trade" (meta)data between facebook, instagram and whatsapp backends and deliver that to law enforcement. I'm pretty sure their ability to do analytics is advanced enough (though even technical people sometimes really overestimate how "good" those big companies are at it). At least at that point they will not have the contents of your messages. Which now they do (with the exception of whatsapp).