I also assume that it will not be impossible at all for Facebook to comply with these regulations, just pretty inconvenient.

This is a common assumption, and it might prove to be correct, but I'm unwilling to accept it as axiomatic.

Fundamentally, just looking at the right of a data subject to withdraw consent, it would mean Facebook needed to track every piece of data that could conceivably be tied back to an identifiable person throughout its entire organisation. That's not just their status updates or that time a friend tagged them in a photo. It's every photo in Facebook's entire database that ever included a recognisable image of them, tagged or not. It's every line in a log file that was saved by an engineer investigating a server glitch that relates to any activity that user took. It's everyone who uploads their contacts to find friends and has one of those data subjects in their contact list.

Now, I'm not saying I think Facebook should necessarily be able to do all of the above. In particular, I have often questioned their hoarding of data from things like contact details and photos that will inevitably include other people who may not have chosen to use Facebook or give their consent.

But I am questioning whether it is practically viable, even for an organisation with Facebook's scale and resources, to follow the letter of this law and still operate at all while continuing to provide similar services, if a few people decide to make a point and explicitly deny consent to hold any data about them, even if such data was supplied by other people. There are practical, ethical and legal issues here about third parties and automated systems that we have barely begun to explore, and we're talking about them at a scale where businesses like Facebook and Google have already had to invent new techniques and strategies for organising data just to cope with what they already do.

None of this has even touched yet on whether Facebook would still have a viable commercial model if users have a right to opt out of processing their data for purposes such as advertising but Facebook isn't allowed to deny them service in return, which is another interpretation I've seen talked about a lot (on the basis that an opt-out that stops you using something independent as well isn't a true opt-out and so wouldn't count). So far, I haven't studied the GDPR and informed reviews of it enough to reach any firm conclusions or opinions on that side of things, but again there are surely issues about the obligations of an organisation that offers a useful service but relies on advertising to fund it that go far deeper than just Facebook and the GDPR that haven't really been explored up to this point.

As surprising as it may seem given my comments in this discussion, I'm actually a pretty firm believer in stronger privacy rights and a confirmed sceptic when it comes to the big data hoarders like Facebook and Google. But I'm also someone who runs businesses and has first-hand experience of what happens when the EU's non-technical legislators meddle in technical issues they don't fully understand, often missing even the blindingly obvious consequences, never mind the more subtle and/or long-term implications. So I don't think we should dive into changes like this without considerable thought, and contrary to what various officials from the EU and the national data protection authorities like to say, I don't believe for a moment that this sort of change is a small, incremental development of the existing privacy frameworks we already operate under.