There are already several main characters from Mission: Impossible - Fallout confirmed to be in Mission: Impossible 8. Tom Cruise's Ethan Hunt once again headlines the film, which could be his final entry in the franchise. Audiences will also see Ilsa Faust (Rebecca Ferguson), White Widow (Vanessa Kirby), Benji Dunn (Simon Pegg), and Luther Stickell (Ving Rhames) come back. That leaves quite a few cast members from Mission: Impossible - Fallout that could return. Still, the nature of the unexpected tease means that it will likely be someone with a great significance or tied to a major Mission: Impossible twist.
Although Mission: Impossible 8's returning Fallout character could realistically be Solomon Lane (Sean Harris), Erica Sloane (Angela Bassett), Alan Hunley (Alec Baldwin), or Julia (Michelle Monaghan), none of their appearances would be that shocking. That just leaves Henry Cavill to be Mission: Impossible 8's returning character. McQuarrie previously teased that he could be involved in the next two movies, even though Mission: Impossible - Fallout's ending very clearly killed Walker. With the original tease in mind and McQuarrie's desire to keep the latest Mission: Impossible 8 cast member a secret, all signs point to it being Henry Cavill.
The decision to bring back Henry Cavill's Walker in Mission: Impossible 8 would allow the franchise to continue exploring one of its best villains. His role in Mission: Impossible - Fallout focused on his time with the CIA while he also secretly was the terrorist known as John Lark. Thanks to Cavill's cocky performance in the movie and the incredible physicality he brought to the role, Walker stood out as one of Fallout's best characters. There was so much excitement for him pre-release that he was even suggested as a possible franchise lead replacement for whenever Tom Cruise's Mission: Impossible journey ended. It would be great to see Henry Cavill get the chance to flesh out this character and become part of Mission: Impossible 8's potentially franchise-concluding story.
It is easy to say that he should come back, but how Henry Cavill's August Walker returns in Mission: Impossible 8 is a bit more complicated. McQuarrie certainly would not pull a cheap move and use one of the franchise's iconic masks to reveal someone other than Walker died fighting Hunt in Mission: Impossible - Fallout's ending. Being impaled in the face with a giant hook and plummeting to the bottom of a cliff also leaves almost no room for resurrection. Instead, Cavill's Mission: Impossible 8 role could come through flashbacks, possibly revealing that he was a much bigger piece in Hunt's past missions. If the movie really is the end of Ethan Hunt's story, then making Walker more of an overarching villain for the franchise could be a nice twist.