Indeed, recycle the engine, add a few more spells, lots more stories, maybe soem new explorable regions around Hogwarts / travel to on the Hogwarts Express, off we go, done. They've shown that if you provide A) 3rd person action with spells, B) a fully-explorable, no loading zones Hogwarts, and C) lots of open world play, you can make a mint. So take my money!
Making the scolds angry is just a bonus.