But, I think the question is, would Ron have won the Quidditch Cup for the team or become prefect if he hadn't seen it in the mirror to begin with? While it wasn't mentioned again, even after these things happens, it's highly likely that it was filed away in his subconscious and while he himself inhis conscious state wasn't actively persuing it, he subconsciously made it happen, a self-fulfilling prophecy. And I do think Harry will see his parents again because I do believe he's going to die in the last book. He will be able to see them once he departs from this life and goes into the next.