I'm pretty sure Chemist or something like it will be the new healer for the next expansion with everyone talking about it and wanting it.

As for me I voted Mystic Knight as its one of my favorite archetypes in a RPG and RDM really isn't doing much with the whole melee thing so maybe make it like a hybrid that goes in for most attacks but has some attacks that lets it stay out of melee ranged? I don't know but I don't think it would hurt to have another melee with the game having 6 ranged dps classes.