Yeah, this feels like the build up to an ending, but considering her last piece ended at only 17 chapters (albeit vol. 3), this feels like a much more successful run.
Honestly the manga has answered its own premise by this point. Can an outcast start over? The answer is an overwhelming yes, and the main issue that made pre-time travel Koharu become a shut in has been solved.
I wouldn't be surprised if it ends right there, because from this point on they can only do;
1. Introduce a new character with some issues
2. Koharu tries her damndest to solve the issue
3. Resolve issue and Koharu gets another harem member.
Repeating this ad infinitum would definitely get stale after a while.
Unless they want to switch to romcom, but I don't think that's what people want from this series.