Somewhere within the chapter, it may not be at the beginning—knowing Akasaka-sensei (writer), he'll mess with us a bit—but I suspect that Ootomo (I used the spelling found on page 20 of chapter 88. Others use Otomo, but it looks weird to me.) will be standing on one side of the hall way, while Ishigami will stand on the other side finally facing her. She will, essentially offer an apology for her behaviour, likely a tearful one. The question I cannot correctly predict is how Ishigami will respond. I'll probably get a lot of hating for the next thing I say, but I do hope Ootomo & Ishigami reconcile in each other's arms. My view is that Ishigami's own pride, pain and love for Ootomo are so mixed up that it may take a bit before he accepts her. Likely his disappointment that she so quickly abandoned him will play a role.
However, a second viable scenario that I see as a whopping possibility: Ootomo and Ishigami reconcile, but without any further developed relationship. Tsubame will have made it clear to Ishigami that she's not really his love, but that she firmly believes she's a mere copy of Ootomo, that Ootomo is truly Ishigami's first love. From that point she veers out of the story. Ishigami accepts, with some pain, her rejection, likewise rejects Ootomo on the basis of her shallowness, and returns to the council room. And then we have the "ship" so many have been waiting for: Iino is there to console Ishigami as he sits playing some game. Then, seeing that Ootomo was soundly rejected, and that Tsubame has gently let Ishigami down, she'll spill on how she feels. Ishigami may not "jump" at the Iino offer, but keeps it as a consideration.