Well, only time will tell, I just relayed what I've heard from people much more knowledgeable in this area than me. How I understand this is that if you serve many enough EU citizens, please be kind, open a branch in EU or at least send a representative, because you are de-facto doing business here. Mainly this is to avoid situations where, for example Facebook, closes its EU offices and pretend to have no EU presence (and no need to abide EU regulations) despite hundreds of millions EU citizens use their services.