The only problem is: Facebooks terms of service isn't really reasonable, and most people won't understand the implications. As I understand the GDPR one of the goals is to give users a set of rights, in regards to their data. These right cannot, under any circumstances, be violated, just as you can't bond yourself into slavery or sign away your right to free speech.

Facebook and others are currently trying to find loophole, like with the cookie-law, except this time the EU did it's homework and companies won't get of with such simple solutions. Really if Facebook believe they can't do business in the EU after the 25th of May, due to the GDPR, then they shouldn't. Just close of all EU activities. Of cause I understand why they won't, the company would lose a good chunk of it's value, but it will anyway if it can't find a way to legally operate under the GDPR.