I still contend that you are going to put 2500 programmers instantly out of work, they will be hired instantly by others, and they will communicate via back doors and WhatsApp with each other, and collude in the dark to make their "friends" apps more successful and better integrated, and just build more impenetrable - and now diversified - defenses against competition. Do whatever you want to the business... the cogs that make that business work, are still going to try and make their job easier (and the product more successful) in whatever way they can. And that'll involve back-channeling with the rest of the people they used to know at the Tech Giant that has just been broken up. Any new competitor outside of that whisper network is going to have a much steeper hill to climb to get to the same place. It is, in a nutshell, why Facebook is evil: It isn't that someone at the top has an evil plan they have put in motion. It's because of the network effect of a million little bad decisions by thousands of programmers on long leashes, with little oversight or concept of what they are doing in the broader picture of the product, users, and society at large. Now, instead of keeping all those evil little decisions wrapped up in one uber-evil organization, you send them all to the wind to do evil on their own... I just don't see that turning out well for anyone.
You're not making their work illegal, you're making the monetization strategy illegal. They don't need to communicate via WhatsApp, they just need to come up with a business model that abides by the terms of copyright law. The problem isn't the business, the problem is the monetization. Facebook is evil because the way they make money is by selling access to their users. There has been no enforcement as to what their users own and what Facebook owns. Change the strategy from "sell our users' data for whatever we can get" to "sell our users' data for an acceptable profit margin because we now have to pay our users" and everything else takes care of itself. No "million little bad decisions" here - Facebook makes more money for better-targeted advertising and there is ZERO cost for increased targeting. Change that cost from "zero" to "anything" and suddenly there's a whole new business model.