Halo & UC2 = FPS game therefore may not appeal to SF fans so who cares
DOA online = 3d fighter, may not appeal to 2d fighter fans
Tekken5 = Console release 2005 not 2004, nobody knows if its going to be online
Mk6? Who cares, MK is shit
Jam probably cost capcom next to nothing to make with a skeleton crew. You forgot jam is meant to appeal to SF fans, its not designed to win over a new audience. Therefore its easy money for them. So no, from a business position it would not make sense to scrap it.
Remeber capcom said 20+ characters. So don’t think this will have a small to average roster just yet. Also, don’t get too locked on teh idea that just because a character is in the background that you wont be able to play him. Maybe as you unlock characters(ken for example) they disappear from the background. I HIGHLY doubt that there will only be 2 representatives from each fighting game(like how ryu and guile rep Sf2) my estimate wil probably be 8 or so characters from each respective game. 10 will be really generous. You might even be able to unlock other games like RE for example. Remember that Capcom could use the Jill sprite from MvC2.