A lot of folks have explained why so many of the classes that are not confirmed will likely be of other power sources. I agree with most of that. I especially like illusionist as a shadow power source caster, rather than another arcane caster. I'm hoping we don't see a ki power source, and think that the monk, if not divine, best fits the feel of psionics and should take over as the primary physical psionics class. It feels more unique and useable to me than the majority of the psionic fighting classes released to date.
Back to the subject at hand. What *will* be in this first power source supplement?
I'm hoping for no more than two new classes. One would be fine. I don't care if they fill the grid, so I don't really care if they put out a martial controller. One martial leader is likely stretching the grid enough, and we believe we are already getting two martial strikers. Perhaps some power sources will be "best in class" for a certain role, allowing for a 3rd striker. Otherwise it would be a defender, and the fighter is so versatile that it boggles me as to how they could make another defender that the fighter can't emulate. My vote, because I think each of these books will have a new character class, has to go for the 3rd striker... perhaps a swashbuckler if it doesn't step on the rogue's toes too much, a kensai type sword saint would be my preference if they want to tie non-western classes into these products rather than an OA product.
I think we will definately see more martially inspired paragon paths and epic destinies. I'm hoping a lot of the prestige classes people are calling for get done through these avenues rather than full base classes.
I think a host of new/alternate talent trees are a safe bet. I assume the weapon techniques, that they claim will make fighters who use different weapons feel so much different from one another, will be handled mostly through talents. This presents the biggest area for martial expansion in my opinion... as we could get talents/feats/stunts, or whatever the martial equivalent to a spell is, for a variety of weapons and fighting styles.