Every time Rika appears, it is always interesting. I want to share a bit of my thoughts.
Looking at how MITA has written the story so far, I tend to think that Rika's desire to see Sousuke have sex with another woman is purely to use it as a tool to exploit Sousuke's weakness. It is as simple as when Sousuke asks why Rika cheated, Rika only needs to answer by showing a video of Sousuke having sex with another woman, while on the other hand, Sousuke has no concrete evidence that the woman in the Ura Aka video is Rika. I always remember how cheap Iwabuchi's answer was when Sousuke asked whether the engagement letter between Iwabuchi and Rika was still valid or not, and Iwabuchi answered with absolute certainty that it was still valid. What an absurd answer of self justification.
Then, regarding what will happen next. I am 100% sure Rika will not get caught or be finished now before Iwabuchi falls first. So there is a possibility that Akiba will fail to catch Rika because:
1. Rika makes a shocking statement that Akiba cannot counter, or
2. Rika invites Akiba to play a game, like a drinking contest, and knocks her unconscious, or
3. Misato, who is peeking, gets caught by Iwabuchi, or
4. Perhaps Satsuki causes a commotion/riot that make allows Rika to escape.