Brilliant, Tony, brilliant! I love your interpretation of the wizard world as parallel to the gay world--the young wizard's gradual recognition of his difference, the sudden revelation that there are tons of other people like him. Do you see a Magic Pride movement starting, with witches and wizards insisting that muggles accept them and grant them civil rights? I'm longing to go to the Magic Pride March--imagine the floats and costumes!
I like your idea of foreign wizardry, too. Did you ever read Kingdoms of Elfin, by Sylvia Townsend Warner? It's another out-of-print work of genius that could plausibly come back on the wind of Harry's success. Warner wrote a series of stories--I think, but I'm not sure, that a lot of them were published in The New Yorker in the '70s--about communities of fairies living in various countries. They're partly exquisite little parodies of travel lit, partly cruel little fables. As usual, try getting a grown-up to read them--you can hear them muttering "Fairies? Come on!" in their heads. But these stories are certainly not children's literature: The fairies are heartless and creepy (which makes them human enough that they're weirdly touching). In Elfhame, in Scotland, here's how they treat changelings:
Every day a fasting weasel bites the child's neck and drinks its blood for three minutes. The amount of blood drunk by each successive weasel (who is weighed before and after the drinking) is replaced by the same weight of a distillation of dew, soot, and aconite. Though the blood-to-ichor transfer does not cancel human nature (the distillation is only approximate: elfin blood contains several unanalyzable components, one of which is believed to be magnetic air), it gives considerable longevity; ... "Dear little thing," said Tiphaine [the queen of Elfhame; all Warner's elfin kingdoms are matriarchies]. "I hope he won't age prematurely." For when grey hairs appear on the head of a changeling he is put out of the hill to make the rest of his way through the human world; which is why we see so many grey-haired beggars on the roads.
The Elfin Court of Zuy, in the Low Countries, was wealthy and orderly. No winter gales penetrated its polished windows; if the summer sun shone too vehemently, blinds were pulled down to protect the furnishings. Drinking bouts were long, taciturn, and ended in somnolence. The Queen was celebrated for her pearls.
It would be fun to take a school trip with the Hogwarters and see what details Rowling would assemble to build national styles of wizardry. But I think your other scenario--a foreign teacher joins Hogwarts--is much more likely. Notice how Rowling structures the books in strict parallel centered around the school: First we get a few chapters of Harry at home with his awful muggle relatives, who lock him in the closet, starve him, and cower at the thought that he might perform magic (his frustration at not being allowed to is part of the amusement of this section). Then we get a visit to Diagon Alley, a hidden street in London where witches and wizards shop for this year's school supplies. Then the trip to Hogwarts, generally on the Hogwarts Express, which leaves from the invisible Platform Nine and Three-Quarters at King's Cross. At Hogwarts, we get the rhythms of the school year: the classes, new teachers, spells gone wrong, midnight feasts, Quidditch competitions, bad marks for mischief, exams, Christmas break, and so on. At some point, usually the climax, we visit the Forbidden Forest, a spot of hazard and wonder, right on school grounds. What's amazing is how Rowling manages to cleave strictly to this formula, yet provide such a wealth of new details and such deep, dangerous plots that every book seems completely new. It's a trick other people have used--P.L. Travers, in the Mary Poppins books, for example, always has a chapter in which one of the kids loses her temper, one in which we visit a relative of Mary Poppins' for tea, one in which Mary has a birthday, and so on. But Rowling isn't just writing independent chapters--her novels have an overall trajectory that deepens and develops from book to book. It's as if she's writing a sequence of sonnets.
(Not a succubus, by the way. A succubus is a female demon that comes to you in the night while you're asleep and has sex with you against your will. I was thinking of a monster that looks like an ordinary woman, until you see her legs--which she doesn't have. Instead, there's a snake tail, or a puddle of oozing rot. I've seen her called a melusine, but I think there's another name. Maybe one of our readers can think of it?)
I'm still interested in hearing your thoughts about the question you posed a few messages back: Why Harry, why now?