We actually did have plans similar to this at one time, and they went beyond PvP to RvR (Realm vs. Realm) or a sort of kingdom warfare. Obviously, that was a huge undertaking and it never really got beyond the planning phase just for the sheer amount of mechanical support it would have taken.
Right, my idea is like a severly stripped down version of this then. Making a few areas and posting signs at the entrances and making messages pop up on your screen, like we have in some areas now isnt a huge undertaking.