Michiru still being alive is good. Oriko might have been able to confuse Michiru and Kazumi, but Nadia wouldn't have, and I can guarantee she would notice the anti-Incubator barrier. Did Nadia actually meet her in person, though? How recent is the information?
Regardless, I don't think this should change our plans to go to Asunaro tomorrow. Michiru witched out due to a combination of being witchbombed (per the last page of her diary, but this might not (yet) have happened) and being a martyr senpai (handing out Grief Seeds to all of her students to ensure that they're safe and happy at the expense of taking case of herself). We still have no idea how close she is to imploding, given that she's a natural optimist and was able to hide her condition from the seven people she was closest to and in frequent contact with.
Airi may not be a threat yet; depending on the circumstances, we may still be able to defuse her-- either by saving Yuuki, destroying her Witch somewhere where Airi can't see it, detaining her Witch for SCIENCE purposes, or preventing The Rat from telling her about it. Even if Kyuubey does tell her (which would be his first openly hostile act against us), we're way more capable of shouldering her grudge then the Pleiades vis a vis Gensokyo Friendship.
Kanna exists, but she may still be ignorant; if so, we want to do our level best to keep her ignorant and avoid socialling her because it would be social landmine for Niko. If she isn't... I realized she's a lot more dangerous than I thought she was on account of Stranger powers. Connecting to people without them noticing means she's a doppelganger who can copy powers; after Niko dies, she infiltrates the Saints by pretending that the real Niko was a spare body she got from her wish (close enough to true that Jyuubey corroborates it, if the other way around) and proves it by using Niko's alchemy powers to blank the face of her corpse. We need to be on high alert at any time we can detect an unfamiliar magical girl in Asunaro, because Kanna copying Sabrina is goddamn terrifying.
Soujus are still a wildcard. Normally I would say they're fucked against the full-strength Pleiades, but prophecy has them either winning or avoiding a fight to head to Mitakihara. If the Saints haven't launched their pogrom yet, the duo might simply hunt some of the surplus loners in the city and then move on, ignoring the local power bloc. They'd be dangerous to Kyouko, Sayaka, and maybe Mami if they make it to town, but get absolutely dumpstered by Sabrina or Homura.