I've come to love the interactions between Yui and Saeki. They often offer a lot of interesting insight on what's going on with Nanami from two very different and privileged points of view.
Plus I tend to like it when "rivals" aren't at each other's throars.
I can't really even see them as rivals, personally. They just both love Touko (who is, which bears repeating again and again, stupendously, inhumanly lucky to have not one but two extraordinary women love her this much), and both are content with just loving her. Rivalry implies that both would aim for the same goal, such as Touko's reciprocation, but they really don't have anything to fight over, so it's more of a bond than a rivalry (even though rivalry itself is a form of personal bond, too).
On the topic of the next chapter, I have a strong suspicion that it will jump directly to the aftermath of the play. I don't see any narrative point of writing out a story-with-a-story unless it goes completely off the rails and turns out to be more about the actors than about their (doubly fictional) characters. Skipping the play to only reiterate the key events and to deal with the aftermath would be a nice piece of elliptic storytelling that I am sure Nakatani would be able to write perfectly.
