Usually, stuff like Throuple/Harem endings are very mixed up with "wish fulfillment" style stories that don't get bogged down with quality writing and narration. So while it's never a zero-percent possibility, I try never to jump to it being an actually viable conclusion to a romance arc involving multiple characters.
That aside - Sunao is absolutely conflicted with his feelings regarding Lemon now that they've had their Big Talk, and the fact that he seems to be actively not looking at them any deeper (I know it's been, like, 24 hours in-story, so 'grace period' and all that), I am a bit uneasy in ascribing the same amount of hope I had for Natsumin being the ending heroine that I had at the end of the previous chapter with her impending phone call.
The fact that it still seems like we're not getting a clear "Natsumin Focused Arc" in the immediate future, at least without Lemon potentially getting injected into the situation, makes it very hard for Natsumin to get dedicated screen time that she requires to compete with Lemon in the narrative sense when it comes to a potential romance component to the story's finale. As it stands now, she can't compete with Lemon, both in terms of history with Sunao, and with total amount of time spent developing her character. She needs that desperately, or she's just going to continue being a veritable prop that propels the other two forward in their own narratives.
I hope there's still a lot of story to be told, and that this isn't ending before we hit triple digits of chapters or something. I know who I'm personally wanting to see together at the end, but I'll accept any ending if we're given the requisite quality of story and attention to each detail and plot point - so hopefully this isn't ending anytime soon, because I could easily see it reaching 100 chapters without "running long" in order to fully tell the story that needs to be told for all three that does them all justice (to say nothing of the support cast).
