JKR has already said that one of the characters ends up as a Hogwarts professor. My bet is Neville ends up as Herbology professor, replacing Professor Sprout. But Hermione is damn good at Transfiguration, and Professor McGonagal is now Headmistress. I loved the killer canaries in HBP.
That’s so weird that you mention the canaries. I am re-listening to HBP and took a break to see if there were any new posts. I was right at the canary part! (insert Twilight Zone music)