Well if that is your opinion than more power to you. That doesn't mean it has to exactly be like you think it will.
I don't see what the abuse is? People changing to PvE when coming to a zone where their spawn is complete blocked off by the other faction in order to get Quests done? That is not an abuse, it is a legit game mechanic. BUT first there would have to be such a situation which would organically be prevented by everybody joining the PvP shard is ACTIVELY chosing to do so. Organic PvP isn't going away, it will shift in size and the way people engage each other.
I just wonder where all this "fear the unknown" comes from. And all those years i did not regret to have rolled on a PvP server, but i very well like where this change can (and most likely will) lead to. And as such a PvP player i can olny say to you and all other doomsayers: just imagine it will be way better than you expect, people fighting across the zones, back and forth between two camps on multiple maps/regions..... you are not there to experience and enjoy the carnage. You'll be sorry that you missed out on all of that ;-)