Manager was doing it by herself before Momiji, so she should be fine. I misread that at first as your thinking long-term and I had the idea that it'd be pretty neat to see an epilogue where the loli that's shown up a few times is now in high school and ends up becoming a part-timer at Momiji's Suzume-tei, hinting that she'll go down the same path as Momiji (maybe taking over for the Manager at Koharuya later on).Momiji will need someone to succeed her as the cook though. If the manager was handling it previously, that would be fine, but with how their roles are divided, she'll still need an assistant to replace Momiji, and do some things she might not have enough literal hands for.
I think it's hinting that Momiji and Aikawa are going to stay together, with Aikawa joining in to help her run Suzume-tei.Still sad that this is somehow not a GL series