Well, I do not comprehend why one would take current NA as a good reference. I stopped playing on NA when EU hit first day , ranked above thirty. When I logged in yesterday my character was still ranked above eighty. Tells me enough about how active/competitive NA is and that it is not a desirable outcome for EU.
Open world and sieges still were the core mechanics for me on retail. The game is dull if one has to hide in dungeons all day long for a white drop or a firm balic material once a month. Whereas I used to farm in Memphis Farm or Undirborg area, including random PvP encounters, waiting for dredgion entry, now I just idle in Inggison being bored. Sadly one could as well just reduce all the maps into a small area offering four daily medal quests where players can gank each other non stop while trying to finish quests. That is pretty much all there is left of end game open world.