Why though? They make gangbusters still and allow them to still tap into the HP franchise. Sequels will come in a few years after this trilogy.I think that WB would be better off scrapping these Fantastic Beasts films, waiting a few years, and then trying to get the OG cast back together for some film set in the future. Whether that is The Cursed Child or something new.
I wonder if they might try another spin-off in a different wizardly world. Maybe strong female character at one of the other schools.