Compairing roles really doesnt work in this game, and tanks have their own problems to deal with (could you imagine tankswaping while having to monitor your resources and having dps spike emnity?) On the side of dps they would have to completely rehaul or remove the TP system to make resource management a viable thing for melee dps (autoattacking as you wait for your Tp is very unfun) Now for new classes id say adding an extra layer of resources would be an interesting idea like say a focus bar for samurai or runes for dark knight and so on.