If Caroline & Mirai fulfill their potential and don't get set back by serious injuries, I think they will both be on the Olympic team. The third spot I think will be dueled out among Kimmie, Ashley, and Rachael. Between Kimmie and the youngsters, Kimmie has the advantage in PCS and experience, so how well she fares depends on how much of her jumping skills she can reclaim. Between Ashley and Rachael, Ashley has the advantage in PCS (speed, basic skating skills), and Rachael has it in jumps (especially a 3Lz/3T that she's been consistently landing -- if not consistently rotating -- since 14). In two years though, Ashley may master a 3/3 (she was close to the 3Lz/3R at SC), her basic triples are pretty big; but Rachael could also steadily improve in her PCS. It's really hard to call more than 2 years ahead of time, which one of these three will come out on top. For that matter, it's not clear what will happen to Caroline and Mirai, what with growth/puberty issues looming.
I do not think, though, that anyone among the juniors or novice girls will surprise us in 2010. Tara, who shot to OGM seemingly out of the blue, won National's, WC, and the precursor to GPF the year before the Olympics season; she also won bronze at U.S. National's and placed 5th in JW two seasons before. Oksana Baiul won the European silver and World title in the season before the Olympics.
I do not see any young lady with this kind of potential waiting in the wings in the US, Japan, Russia, or the JGP's in general. Young skaters get much more international exposure now through the JGP series (created in 1997). It's very unlikely some young phenom can get to the Olympics without getting some notice at the junior level, plus the age rule now in place... I don't think there's time left form the 2010 OGM winner to be someone who is not yet doing well in either the junior or senior level now.