I know it's been mentioned elsewhere, and it would really be more of a 'support' class which is in several different threads- but would the idea of basically a ranged support replacing a tank work? Probably still have threat issues I suppose. But thy could shield a target against damage (basically making anyone a tank) or have spells/abilities that reduce how much damage the targets deal (so that it doesn't matter if they're tanked). Probably too OP. Just a thought to add to the conversation.