There are some very interesting rumors coming out of Eurobricks of a theme that has sort of ended but may be coming back in 2018. The reliable Sir von Lego has said that LEGO Harry Potter will be sets coming next year and there’s also a hint from rob-ot5000 saying there might also be a Collectible Minifigure Series coming out of Harry Potter as well. There was also mentioning of The Wizarding World of Harry Potter but how that ties in to this whole thread remains a mystery. It is worth noting that The Wizarding World of Harry Potter encapsulates everything from the films and the books by J.K. Rowling and Fantastic Beasts 2 will be coming out next year as well so there might be sets and/or minifigures for both the original Harry Potter series and Fantastic Beasts.
The return of LEGO Harry Potter is some very exciting news since the last time we had official LEGO sets, besides LEGO Dimensions, was in 2011 which is the time I returned to LEGO. Keep in mind that these are just rumors and are not confirmed until LEGO announces it.