RO could use new versions of it's existing expansions (Louyang, Amatsu, Brasilia, etc) with new NPC, monsters, items, lore, etc. But at that point it's basically making another game from scratch. Not to mention how the standard korean MMO design with obligatory need for grinding will always kill it in the long run.
At least these attempts are nice. And these events are great, hope they stay fixed every 2 weeks or something, and only happen if they can meet a minimum quota of anons joining.