I would really like to see now all of the major companies block Europe. Youtube, twitter, facebook, google. Just a total immediate blackout. I'm an European with self defeating tendencies.
But why on Earth would they do that? And why should they?
I don't think so. You don't build a second Twitter, Youtube or Facebook in "a couple of months". Plus, all of them would need to deal with GDPR and the copyright directive. So, despite the technical effort, there is also a huge legal effort.
Why the heck would they block the market that just made them easy monopolists?