Rogue: Demon-hunter; Kinda like the Diablo3 Demon hunter. A poison-crossbow wielding stealth-range enthusiast. Or a Saboteur that uses bombs... maybe even leave a bomb in a pick-pocketed target Hehe.. boom.
Monk: Zen-master: Another dps spec that relies more so on ranged spell casting.
Hunter: Artillery; Gives them massive range and strong bombardment spells, but at the cost of movement and mobility.
Shaman: Spirit spawner: A pet class for shamans.... As an off-shot idea, making them tanky again would be weird, but I'd love the unique pet-spawning-tanking class.
Priest: Illusionist; Not so much a healer, or a dps... this is a straight up support to make things die quicker spec. Lots of CC and mimicry.
Of course the rogue one wouldn't be a demon hunter at this point, but the idea is still the same.