The first trailer for Jared Leto's Morbius dropped today and plenty of fun was made about the abject '90s-ness of it all. The trailer delivered on (and in some cases exceeded) our expectations for what a ripped Jared Leto vampire flick would look like, but what gobsmacked the BMD crew the most was Michael Keaton's grinning cameo in the trailer's post-title stinger. "WHO is Michael Keaton playing and WHY is this trailer placing so much emphasis on his appearance when Jared Harris (the good Jared) is standing right over there?", we naively asked ourselves. "Surely this cameo isn't hinting at a connection between Morbius and Keaton's other appearance in a Spider-Man related film, Spider-Man: Homecoming where he played The Vulture. Hopefully this hinting at the Jackie Brown-Out of Sight instead."
Well, we now have to consider the possibility that Sony has finally drummed up the nerve to make that Spider-Man villains/Sinister Six shared universe that they have been threatening to make for years. Ever since the first Amazing Spider-Man movie was on its press run, Sony has been floating the idea of villain-centric Spider-Man films that would eventually lead to an Avengers-like team-up film in the form of Sinister Six (nevermind the fact that the Sinister Six is mostly made up of two-dimensional, bit part Spider-Man rogues.) Those dreams partly solidified when Venom grossed almost $1 billion, giving Sony license to start working on other villain spin-offs like the aforementioned Morbius, and a film about Kraven the Hunter.
With Venom's success, Sony's Spider-Man villains' shared universe became inevitable, but what was a lot more ambiguous was the role that Sony's other, concurrently-running Spider-Man series (y'know, the one that actually has Spider-Man in it) would play in all this. The Spider-Man: Homecoming series and all of its characters exist in the Marvel Cinematic Universe, which is produced by Marvel Studios, not Sony. It's safe to say that Marvel Studios has an interest in controlling their brand and all of the properties associated with their name, hence their insistence on producing Tom Holland's Spidey films themselves as well as the recent closure of Marvel Television in favor of a television production arm that will fall under Kevin Feige's purview.
Back when Venom was still in development, Marvel's need to control every aspect of their films and Sony's desire to capitalize on their successful partnership seemed to be causing a conflict between the two studios. While promoting Spider-Man: Homecoming, Sony Chairperson Amy Pascal made comments suggesting that Tom Hardy's Venom would exist in the Marvel Cinematic Universe alongside Tom Holland's Spider-Man, and Kevin Feige's bemused reactions to these comments became a meme. A back-and-forth of conflicting clarifications from the studios ensued, with Marvel Studios and Feige insisting that Venom would remain unrelated to the MCU, and Sony claiming the exact opposite. Both studios eventually agreed on the line, "Kevin [Feige] makes characters in the Marvel Cinematic Universe. These characters are separate... [but] never say never."
The statement was a compromise that kept the ball in Marvel Studios' court while also being open-ended enough to keep Sony's investors happy. It also seemed to work, because Sony's Venom and both of the MCU Spider-Man movies came out without either of them having to acknowledge the other's existence. But then the terms of Sony and Disney/Marvel's Spider-Man partnership had to be renegotiated this past summer. A couple months before then, seemingly in anticipation of said renegotiation (and probably also as a response to Venom's near billion-dollar gross), Feige ceded that a potential Spider-Man and Venom crossover would be "up to Sony. Sony has both those characters and, has Venom in their world," even going as far as to say that a crossover "seems likely at some point."
While we do know that Marvel was able to acquire the reins for at least one more Spider-Man film, we don't really know what they had to give up in order to get this new deal. Previously, Tom Holland's Spider-Man and his supporting cast we're agreed to be under the supervision of Feige and Marvel, so Sony couldn't use them in their spin-offs. (Although the actual terms of the IP haven't been made clear, so it's a little blurry what elements could or could not be legally shared between the studios.)
With the Morbius trailer, we might be getting an indication of how Sony will treat the Spider-Man IP moving forward. If Keaton is, in fact, reprising his role as Adrian Toomes in Morbius, then there are a number of arrangements that would make this crossover possible. The most extreme (and very unlikely) possibility is that Marvel/Disney has allowed Sony to make a film canonically within the MCU, making Morbius the first MCU film that wasn't produced in-house. Another explanation is that Sony cast Keaton in Morbius without any involvement from Marvel/Disney and used loopholes (like having Keaton appear and act like Toomes without actually being named "Toomes" or employing Vulture iconography) to avoid legal action while also creating the illusion of a connection to MCU. Or maybe there's been an arrangement that falls in between, like Marvel giving Sony to use Keaton's Vulture, but only Keaton's Vulture, and to leave the rest of the MCU untouched.
The most interesting form this crossover could take would be if it signals a sort of "slow denouement" to Marvel and Sony's experimental Spider-Man collaboration. Marvel Studios gets to finish their Spider-Man trilogy, while Sony gets to gradually bring in the characters Marvel Studios popularized, in order to springboard into their long-gestating Sinister Six film and shared universe. You should take this with a grain of salt, because there hasn't been a report about Sinister Six or any villain team-up film since 2015, but with all Spider-Man-adjacent films they're making, it's hard to imagine that Sony has dismissed the project entirely.
On the Marvel Studios side of things, it doesn't seem like Feige or anyone in the company has seriously considered crossing their films with Sony's spin-offs. Kevin Feige reportedly gave notes to Venom's production team, and Sony allegedly toned down Venom's original R-rating in order to make an eventual MCU crossover more palatable with Disney, but aside from Feige's comments about the likelihood of a Spider-Man/Venom crossover, the studio hasn't publically indicated a plan to bring their characters and films into said crossover. So rumors of Jared Leto's Morbius or Tom Hardy's Venom appearing alongside the Avengers are pretty overblown at this juncture.
So here's the quick breakdown: is Michael Keaton playing Toomes in Morbius? Maybe. If so, does that make Morbius canonically part of the MCU? Almost definitely not, but none of this is real, so it can mean that in your head if you really want it to. Is Sony even allowed to use MCU characters? They own the film rights to all the Spider-Man characters, so they can use Spidey, Vulture, Mysterio, etc, but it's unclear if they can use the MCU incarnations and their actors. Will Andrew Garfield ever reprise the role of Peter Parker? Yes, if Sony keeps making movies with the assumption that Evanescence is still charting on the Billboard Top 100.