There are a lot of questions that fans had following the end of Spider-Man: Far From Home. The revelation to the world that Peter Parker is Spider-Man will change everything for the wall crawler. However, one of the other big questions floating out in the ether is the question about Mysterio himself.
The man appeared to be dead following his battle with Spider-Man, but as even those not familiar with the character of Mysterio from the comics now know, Mysterio is all about misdirection. He's great at making people believe things that aren't true, so the possibility that he was able to fake his death certainly lingers out there. One fan thinks he's got evidence that's exactly what happened.
The item at issue here is that, during the news broadcast that shows Mysterio revealing Peter Parker's identity, Mysterio is wearing his costume, which is created via holograms, meaning his team made a point to make sure that was done. In addition, there's a question as to exactly when Mysterio would have created the video.
from r/marvelstudios
During the actual scene where Mysterio is down and Spider-Man takes down the drones, Mysterio's illusory costume isn't visible, the tech is down, but in the version of the scene shown in the post-credits scene news broadcast, the costume is there, meaning it had to have been put back in by Quentin's Beck's team.
The idea, from Reddit, that the video had to have been created after Beck's "death" and therefore he must be alive, is interesting, but I'm not sure it's ultimately compelling. On the one hand, the video certainly had to have been created after the battle between Spider-Man and Mysterio was over. The audio of Spider-Man ordering the drones to be destroyed was taken from the end of that fight, so it must have been made after the fact.
Having said that, it doesn't mean that Mysterio is necessarily alive. Beck could have filmed himself revealing Spider-Man's identity earlier, or the entire scene could have been created by his team on Beck's orders after his death. It could have been a sort of fail-safe plan if things didn't go as Beck hoped.
The idea that Beck must have filmed the identity reveal after the fact because there wasn't enough time for him to do it otherwise would appear to be true based on what we see in the film, but movies can always play with time a bit and find the time if they need it.
Still, while I'm not sure any of this definitively proves that Mysterio is alive, it certainly shows that he could be. Whether or not he is may depend greatly on what's next for Spider-Man in the movies. If Mysterio needs to be alive, because somebody has a great idea for a story, and Jake Gyllenhaal is willing to retrurn, then Mysterio will be alive. If not, he'll likely stay dead.
