Yes i did have a look at it with a Hexeditor
so far i've found lots of references to files wich MIGHT suggest that there are more "unlockable" fighters, all fighters from MKDA have some movelist in there, although it has only one or two moves listed for each style, many still have another reference to their old styles also, so they might be in there.
but this is not definite proof of them being playable at all, only that their files are still in the game
Firestar

yeah i just tryed that too....
i didnt see anything that actully would give us a clue to anything really
but
there is a lot of fighters data there a lot
i allso went to gamespot.com and watched some of the interviews with boon and the others
there right they did mention "quote" MoreThen 24 Fighters"