According to Brickset, a mini set of Diagon Alley (40289) has been seen on shelves in a Slovenia LEGO Certified Store.
The set consists of Gringotts Wizarding Bank, Ollivanders, Flourish & Blotts, Quality Quiddich Supplies and Weasley’s Wizard Wheezes and it also includes an exclusive Ollivander minifigure.
So far no pricing or release date information at this but it looks like the set actually exists and is the same scale of Hogwarts Castle (71043).
What do you think?