I'm with pessimists - unless they already developed it, I doubt they ever will. The would need to create 4 advanced classes and 10 talent trees to keep up with their set up, not to mention all the voice acting for the main characters, 10 companions, and all the NPCS they encounter. It would also require some balancing for already existing classes.
But if that was possible - I would love to see something unique. Something like a Mesmer class in GW2 - like a politician class (that some already mentioned) that would literally talk enemies to death and inspire allies to silly self sacrificing deeds :-) like a mix of healer, buff bot, and DOTer.