I thought there were some tweaks made in FC2. The A-10 certainly felt a bit different from FC1, but I never did a real test to see how.
If you're talking Su-25-style AFMs, I think it safe to say that's not happening. My guess is FC3 will just be the planes from FC2 brought into BS2/A-10C's terrain and GUI with various updates of a more minor nature.
The Jedi Master
The anteater is wearing the bagel because he's a reindeer princess. -- my 4 yr old daughter