The Brick Fan directs our attention to a Eurobricks thread that suggests that LEGO Harry Potter will return as a theme, as well as providing a series of Collectible Minifigures, in 2018. This information verifies – to an extent – information Brick Fanatics has received.
Indications are that the Wizarding World of Harry Potter will be a umbrella theme for classic Harry Potter content as well as sets based on the new Fantastic Beasts movie that is due for release in November 2018. The theme is much more likely to be confirmed as official news in the coming months than the Collectible Minifigures series, which Brick Fanatics has no information on.
All rumoured information should be treated as such until official announcements come directly from the LEGO Group.