Mao is pretty much the only lock. Ando is very close to a lock IF she comes back in the same form or very close to it when she left. Suzuki and Murakami both are up in the air, and it will depend on the season and nationals if Ando is in the running, if not, it will be those two that will go with Mao. That being said, if Ando skips the GP, and finishes off the podium behind both Suzuki & Murakami, she also will not be going.
Mao is the only one who does not need to finish on the podium at nationals to go barring a GP disaster, but even in that scenario.... :S hard to say.
Although come on people, the realistic podium at japanese nationals is probably going to be: 1st - Fumie Suguri, 2nd - Mao Asada, 3rd - Miki Ando. Then I'd be REALLY interested to see who they send, lol.