Something to keep people interested long term, WvW as it is now is good, sure there is always room for improvement but the base is very solid. But I feel like some kind of ranking/progression system to go alongside would really benefit the game, as it is now rewards from WvW are either very small or none depending on your view point.
Realm Points in DAOC were a major part of the game and the sort of system that will prevent people from getting bored of the feature too quickly, because I fear in it’s current state as a ‘just for fun’ mechanic, this will start to happen sooner rather than later.