Warning: Spoilers for Fantastic Beasts: The Secrets of Dumbledore.
If Grindelwald’s rise to power as a Dark Wizard. Fantastic Beasts 5 would most likely end with Dumbledore defeating Grindelwald in their famous duel.
However, after the premiere of Fantastic Beasts’ director David Yates has also signed on to direct another movie—Pain Hustlers, starring Emily Blunt—which means even if Warner Bros. greenlights the film, production won't begin anytime soon.
Just before The Secrets of Dumbledore’s release, Warner Bros. announced that Fantastic Beasts 4’s development depended upon the third film's success. Perhaps as a precaution, Fantastic Beasts 3 wrapped up many of the series’ storylines. The Secrets of Dumbledore confirmed that Credence Barebone was Aurelius Dumbledore, but he was Albus’ nephew rather than brother. In addition, Queenie Goldstein and Jacob Kowalski reconciled and married each other, no longer afraid to be together as a witch and a muggle. Perhaps most importantly for the central plot, Dumbledore and Grindelwald finally broke their blood pact, which had prevented them from directly fighting each other. Despite these satisfying outcomes, The Secrets of Dumbledore left several storylines unresolved in case Warner Bros. continued the series with Fantastic Beasts 4 and 5—particularly Dumbledore and Grindelwald’s duel.
Given that Dumbledore and Grindelwald’s duel was supposed to be one of the greatest wizarding duels ever, it would be disappointing for the battle to never make it on screen, especially since the entire Fantastic Beasts series has been building up to it. The Secrets of Dumbledore gave viewers a hint of what the duel would be like, featuring Dumbledore and Grindelwald briefly fighting in another dimension when their blood pact broke. Their final duel would have much greater stakes though. Dumbledore’s victory marked a turning point in magical history and the defeat of the world’s most powerful Dark Wizard at the time. In addition, Dumbledore won the Elder Wand, one of the three Deathly Hallows, from Grindelwald in this duel. Based on these factors, their epic duel would be the ideal finale for the Fantastic Beasts series, and canceling Fantastic Beasts 4 without showing it would waste the character arc the spinoff franchise had set up for Dumbledore.
Similarly, there are a few other story threads that The Secrets of Dumbledore did not complete. Although the “About the Author” section in the Fantastic Beasts and Where to Find Them guidebook mentioned that Newt Scamander and Tina Goldstein were married, the pair have barely addressed their feelings in the Fantastic Beasts series thus far. In addition, The Secrets of Dumbledore foreshadowed that Aurelius was going to die shortly after his reunion with his father, Aberforth Dumbledore. However, since Aurelius did not die on screen, there is still a chance that he could return in future films. In this way, Fantastic Beasts 4 would create the opportunity to finish storylines such as these, especially Dumbledore and Grindelwald’s duel, that have been key to the Fantastic Beasts film series.
