Exactly, except that we don't have to imagine anything. If Facebook were to disappear today, there already exist many companies with similar business models willing to take its place. Some more willing to cross the line than Facebook.
This is the critical point virtually all criticism of Facebook often fails to address. Sure, you could regulate to death/kill Facebook tomorrow with legislation in country X. All that happens is a clone launches immediately overnight from a country with less onerous regulation, one that anglosphere legal systems will have even less direct control over than the Facebook we have today.
FB, for all its flaws, is at least still based in a democratic nation and operates within a (_relatively speaking_) fair legal system. That the FEC is able to demand (and force implementation of!) regulation already at FB is evidence this works, at least a little. Better the devil you know as they say...
We can't remove the natural human desire to connect to one another on the internet (and associated problems). For me personally, the cat is out of the bag - you can't rewind time and uninvent the underlying communication infrastructure. If people want a social network, the internet will make it for them again and again and host from whatever polity/region allows.
Regulations are never for particular companies, that would be legally untenable. Whatever regulation a country comes up with for Facebook will also affect any other company trying to get into their footsteps. Regulation is the only way to prevent companies from abusing their positions of power. The idea is illusory that they would do it voluntarily even if they could make a profit. Some of them might under some leadership, but not in general and not all of them.
