In blog post, Niantic CEO John Hanke announced that players will "learn spells, explore their real world neighborhoods and cities to discover & fight legendary beasts and team up with others to take down powerful enemies." This means that while the app will resemble Pokémon Go in that it'll be AR-based and we'll be out in the real world showing how nerdy we truly are, it might be more similar Niantic's previous game, Ingress.
"The mechanics of Ingress would actually translate pretty well to the fictional Harry Potter universe, and seems almost ready-made for a fantasy spell casting coat of paint to replace its science-fiction special forces veneer," TechCrunch speculated ahead of the company's announcement. A Fantastic Beasts spinoff would've been an easy cash-in if Niantic wanted to simply rehash Pokémon Go, but it looks like the company is making something new and specific for the Harry Potter universe.
So far, that's all Niantic will say about the game, but the company promised more details will be revealed in 2018 via the official website, Twitter, and Facebook page. In the meantime, just look forward to awkwardly yelling Expelliarmus as you fling your iPhone X off a balcony (not even an augmented-reality Reparo spell will fix that).