Reading this as a future prediction to their relationship is strange with the current level of their relationship, they feel a whole lot more comfortable and close in the recent arc then pictured here.
Was thinking the same thing and honestly is not something we can take for granted, it could have easily ended like this, a "flanderization ending" a flander flounder.
Let me give some examples:
Teasing master Takagi San, in the sequel series he is stil just as stiff as back in elementary with her wife despite having had a daughter, this doesn't make sense unless he is neuro divergent in some way, anyone would have gotten used to it.
Dress up darling, Gojou being awkward, embarrassed and anxious with her up until the ending except for the volume extras.
Is like the author could only project a partial idea of how people can change.
Thanks for translating up the extras too.