I'd agree with Kilta. Unless they do something crazily drastic and remove the ability to level anything but one single class, most of the content is going to have to be repeatable - at least to some extent. I haven't played Final Fantasy XI, but I like the sound of defending against the enemy with the chance to 'lose out', be it Beast tribes or Garleans or the Star Marmot Army.

The short lived Tabula Rasa had bases you defended against the enemy alongside other players, and that was probably the best thing about it - working together towards a common goal, without the need to worry about organisation *too* much, but with a nice community building aspect about it.