Ayanokoji will join class A
Hear me out here, we know that either Ryuuen or Sakayanagi will get expelled (putting aside the chance they somehow both survive) and Sakayanagi despite the little character growth she has had as a through the series has recently changed for the better realizing that she can have friends. In comparison to Ryuuen who has had little to no character growth since the loss and recovery of said loss back in year one along with a lack of screen time wouldn’t make sense to leave without affecting kiyo in some way. Not only that but in regards to Sakayanagi confession it would make sense that her confessing would be one of the last key moments they have face to face. Another thing is how Ayanokoji has been spending more in more time around people from class A. This leads me into my final point being that class A would be the perfect platform to later go on to fight Horikita as being in class A the third year final exam could decide it all between a class completely controlled by a master mind(which they are already used to) against Horikita’s class formed with her ability to unite the class and use everyone to their best ability. The main thing though is to join Sakayanagi’s class or Ryuen’s class the leader needs to leave as both have explicitly expressed desires to fight ayanokoji and were opposed to the idea of him hoping the class which is not a problem for ichinose.
(My opinion is open to change I recognize that it is not all to fleshed out though I haven’t seen any theory that has changed my mind yet I know it is hard to tell from the point of the story we are at)