This article contains spoilers for WandaVision episode 6.
The latest chapter in WandaVision once again has viewers eagerly picking up new plot details while also scratching their heads trying to make sense of it all. This episode in particular brought up more questions than it answered, but it moved the plot forward in such interesting ways that fans can't wait to see what happens next. This is mostly due to the inclusion of Wanda's previously thought to be deceased brother Pietro reappearing as the version of Quicksilver from Fox's X-Men franchise.
Or is it? After the Evan Peters version of Quicksilver appears on Wanda and Vision's doorstep at the end of episode 5, it's implied that Wanda's brother has been "recast." This could mean that the inclusion of this version of Quicksilver is more of a cheeky nod than it is a definitive confirmation that the multiverse actually contains all of the mutants from the original Fox franchise. It also begs the question of whether or not mutants officially exist within the MCU. While that would be incredible to see and the emergence of mutants within the MCU has long been wanted by fans (just imagine, Hugh Jackman returning to team up with the Avengers!), the world has yet to receive any such official confirmation.
Marvel remains tight-lipped on the subject, partially because half the fun of WandaVision is the speculation concerning all of the characters and the mysterious plot from week to week, but also probably for a number of other reasons as well. For one, Marvel is most likely going to take its time introducing this element from the Marvel comics due to how much additional complexity this would add to the MCU. Imagine if in the next Doctor Strange movie, which is supposed to deal heavily with the multiverse, were to also have to deal with the ramifications of super-powered beings popping up all over the place. Or for that matter the upcoming Shang-Chi and Blade films. Shang-Chi will introduce an entirely new area of the universe akin to the world's first visit to Wakanda. Blade will introduce vampires. Adding in mutants to the mix is a tall order should Marvel wish to keep their runtimes at respectable lengths.
Then take into account the civil rights aspect that would be introduced with the official confirmation of mutants. The governing bodies of the world weren't exactly keen on the Avengers interference in Avengers: Age of Ultron. This directly led into the events of Captain America: Civil War, in which the plot centered around the need for oversight of super-powered beings. Confirming mutants exist within the MCU means that the world would change drastically, with governments around the world rushing to try and bring some control over the rise of so many people now having supernatural abilities. This also brings up the issue of how Marvel would be able to find ways to introduce these characters.
Marvel is known for finding fun and interesting ways to bring in characters to their universe that are faithful to the comics but also add fun spins to the what audiences expect. Like the introduction of Black Panther and Spider-Man into Captain America: Civil War. The X-Men have already had two franchises essentially, meaning that audiences already know about the majority of these characters. They'll most likely want to introduce them into upcoming films as they go, which makes their inclusion into the next phase of Marvel films unlikely at best, as much of the planning for this phase was completed a long time ago.
Some might think that the inclusion of classic X-Men costumes from this week's Halloween-themed episode is Marvel's way of hinting that mutants may be on the way. However, these are most likely cheeky nods to the character's history within their comics. In the comics the distinction between mutants and heroes has existed for some time, so it's not like Marvel had a choice between a "hero" costume and a "mutant" costume for characters like Scarlet Witch.
The reason for this line of thinking is that, just like Vision in episode 4, Pietro is revealed to still very much be dead. He's moving by some form of magic, though we don't know if this is Wanda's doing or if there's something more sinister at work behind the scenes. This means that while the casting of Evan Peters as Quicksilver is a clever reference to the other X-Men franchise, he's still most likely the same corpse of Pietro that died in Avengers: Age of Ultron.
Lastly, it's important to remember exactly how Marvel originally got around the mutant phenomenon when they hadn't purchased Fox. Wanda and Pietro received their powers through experiments with the Mind Stone, they weren't born with them in the MCU. Marvel has to account for mutants being people who are born with supernatural abilities through genetics alone. For this reason, it would make more sense for her and Vision's children to be some of the first mutants. The marriages between current heroes would be the most logical starting point for mutants. This would allow for the genetics of heroes to get passed to future generations and for Marvel to stagger out their introductions into the MCU. But who knows? Either way, the twists and turns ahead are sure to shake up the DNA of the MCU itself.
WandaVision releases new episodes on Fridays on Disney+.