Regulators will regulate (once they get started)
Mmh, “regulate”, really? I really hope there are enough outspoken tech-libertarian and crypto-anarchist users of the early Internet left, who will not fall for regulation as a solution. As we have just recently seen in the lost fight against upload filters in the EU, regulators have an unsatiable appetite to churn out more regulation, in favour of whoever lobbies them around, once they discover another domain that is responsive to regulation. Innovative cryptocurrency and blockchain projects are doomed as well once governments discover ways to regulate there. (That space is admittedly a bloody Wild West scenario right now, but why not. At least it’s innovative!)
Too big to exist
So if regulation can not save but only destroy the Internet we loved, what then? In very short: everything that is large enough to cause serious social issues (like, well, Facebook in this case) should either (1) not exist at all or (2) be public infrastructure, preferably distributed and open source, and certainly not in private hands or (3) consist of small federated units so it cannot cause such serious problems.
The case against advertising
And while we are at it: most issues with tech giants somehow revolve around the use and abuse of advertising. Both in the case of Facebook and Brexit, and in the conflict between publishers and Google over the share of Internet advertisement revenue (which is behind the whole upload filter and link tax debate of the EU copyright reform). Now advertisement is organized bullshitting and misleading of people anyway, and the Brexit campaign example makes the hypocrisy of political leaders blatantly obvious: in their eyes, organized bullshitting of people for economic growth is fine (even though overconsumption means ecological destruction, but who cares) but organized bullshitting of people for other causes is “a threat to democracy”!?
So if we want to save the Internet, and a good part of the natural world alongside, let’s get rid of advertising altogether, both online, in print, on TV and in public space, whether for products or political parties. It will create some disruption, but the Internet will find other business models, no worries. To get rid of advertising online, I am even willing to accept a tiny bit of regulation: all major browsers must come with an ad-blocker enabled by default.
(P.S.: Re-reading this, I like my style of writing when I’m angry 
It sounds a bit like @hexayurt now, and I always wanted to know his secret of writing.)