J.K. Rowling was planning two more Fantastic Beasts films, however, the previous two were unimpressive which resulted in the final two being cancelled. However, the Harry Potter Franchise is still going on in some mediums. So I have a solution that J.K. Rowling should take seriously, an idea that could save the franchise.
The reason Crimes of Grindelwald and Secrets of Dumbledore flopped is because they weren't based on books, they were made specifically for film. In the screenplay for Secrets of Dumbledore some fans say that it should be a full book rather than a Screenplay. Also the series needs to drop the Fantastic Beasts title because that was only used to lure in moviegoers by connecting it to the guide book.
I Think J.K. Rowling should write two more novels to complete the Fantastic Beasts series her way but give it a new title. If the novels are a success Warner Bros might reconsider the franchise and adapt them. If not we would at least get an end to the saga.