Not being a game designer, I'm assuming that new class concepts are incredibly hard to come by. Original is a pretty high bar in and of itself. Add Necessary, Interesting, and Fun to the list of requirements and the task becomes monumental.
But, is it too late for new class ideas in the APG. So far, I'm not too keen on the first two releases (sorry guys). I've been told not to criticize without a suggestion . . . so here it is:
Very Basic Concept: Pathfinder has introduce a new mechanic into the game, Combat Maneuvers. The game is looking for a battlefield control class, comparable to the v3.5 Marshal. Why not build a class around the ability to add a characters "controller" class level (or 1/2 of) to the CMB? Add a few team buffing abilities and you already have a welcome addition to any adventuring party. With all the CMs available, you already have built-in variety for the character without adding any new mechanic.
Just a thought . . .
P.S. If this has been done before, please tell me where . . . because I missed it.