I can tell you what really would have happened
Hana would have come into Miyako's life and left Matsumoto aside (Or it wouldn't be the same anymore), no matter how close friends they would have been
Some things can never work out.
You made a Wataten-themed account in order to comment on this manga? 😆
A lot of possibilities can happen when we're talking about choices.
Sure, Miyako might just jump to Hana when they meet years later, but there's also a different possibility where Matsumoto not only manages to win Miyako's love, but together manage to sort out Miyako's social anxiety. And being able to work out your problems with someone's support is something that can strengthen Miyako's bond with Matsumoto even further.
This is to the level that when Hinata brings Hana home, Miyako probably won't even feel anything beyond friendliness, because she's already secure with Matsumoto.
So while it's an interesting idea that Miyako and Hana meeting is "destiny", it's fun to imagine a different life for Miyako.