Thanks for the kind words Thrivenbard. I'll be doing another class thread real soon.
In terms of 4th specs, I think it would be better if Rogues became a healing spec, and Hunters becoming a tanking spec.
Here's the breakdown for the hybridization of the pure specs;
Rogues: Bard
Play style: Rogues use ranged weapons, and their combo system is used to determine the duration of their song and healing abilities.
Hunter: Beast Master
Play style: Melee based Hunter that uses aspects and pets to tank. Old BM spec becomes Ranger, and Marksmanship becomes the pet less Hunter spec.
Mages: Time
Play style: Uses time magic to heal wounds and regulate damage.
Warlocks: Apotheosis
Play style: Permenant Demonic transformation. Similar to the glyph .