I'm okay with this ending, it feels like Shou brought it as close to the yuri side of it as he could and left it there.
In a standard issue romance novel this is the part where Keiko goes offscreen for some reflection only to return after a timeskip to sweep Ran off her feet. She's even going back home to deal with that situation, it's just offscreen character progression all day every day. So, assuming whatever contract they were under with the magazine didn't let them go full yuri with it(it's still mostly a stretch/gag manga after all), it's a great setup for either a proper continuation or a a nice doujin to finish it all up.
That said if it is a time skip thing I hope it's a long one where we come back to a wife n wife type situation, the offscreen reflection thing is so overused I don't want one here. Skipping ahead further and tell the story through flashbacks just like it was done here would be nice.
Also, since I never got to say this earlier on in the thread: Ran was basically gay for Keiko from day one, trying to compete with Keiko's boyfriend is what got her into health/medicine, and trying to beat your love interests partner to win their affections by being better is crush 101.