*Snape turns out to be Harry's real father...Harry is the result of a few too many butterbeers on Lillie's part.
*Malfoy, Crabbe, and Goyle open a law firm together.
*Harry ends up in jail, for "magicking" the books in his adult job as an accountant.
*Ginny Weasely becomes an exotic dancer.
*Ron is usually found at the Leaky Cauldron, passed out with a bottle of cheap wine in his hand.
*Hermione enters into a "relationship" with Professor McGonagall, as does Hagrid and Neville Longbottom.
*Seamus Kennedy becomes a politician.
*Draco's mother becomes fed up with her husband and turns him into a garden gnome, albeit an ugly one.
*Hogwarts itself reopens as part of the Eurodisney complex.