Before Tom Holland brought Peter Parker into the Marvel Cinematic Universe, Sony unveiled its plans to make a Spider-Man Cinematic Universe. The first two films in this proposed franchise were Venom and The Sinister Six, which were intended to exist in the Amazing Spider-Man universe. Even though Amazing Spider-Man 2 laid the groundwork for the Sinister Six, that film's disappointing returns brought Sony's desire to build a world around Spider-Man's villains to a halt.
After Sony and Marvel Studios began working together to bring Spider-Man into the MCU, Venom was released to tremendous commercial success in 2018. Following the revised Sony/Disney deal, many people assumed Sony would further develop their Spider-Man universe. While it's still not clear if Peter will appear in Venom 2, the first Morbius trailer featured Spider-Man on wanted posters and a surprise appearance from Michael Keaton's Vulture. Both of these factors seem to back up Sony's claims that The Sinister Six still might happen.
The Original Sinister Six
The original plans for a Sinister Six film are mostly shrouded in secrecy and defined by uncertainty, given the little information we have on the film. The end credits and final scenes for The Amazing Spider-Man 2 indicated that the film would've seen Rhino, Vulture, Kraven the Hunter, Mysterio and Doctor Octopus making up the iconic Spider-Man villain team with Harry Osborn, Sandman or Scorpion being added to the sixth slot.
The script, written by Drew Goddard, was teased as a redemptive story for the six villains. However, it's not clear how much of a role Spider-Man would have had. Goddard would later go on to work on the first season of Netflix's Daredevil, and the script, for better or worse, led to nothing. The proposed release date of November 11, 2016 came and went, and we heard nothing about The Sinister Six.
By this point, Spider-Man had already been rebooted into the MCU, removing the foundation upon which The Sinister Six franchise had been built. While Amy Pascal has confirmed as recently as December 2018 that plans for The Sinister Six were still ongoing, there was no information provided about the film, and there was no concrete proof of the Sinister Six movie.
After all, the script would likely need to be drastically re-written if it were to be used today. Since the MCU Vulture debuted in Spider-Man: Homecoming, he would be different from the Vulture that could exist in The Amazing Spider-Man's Sinister Six, where Oscorp would've made the villain's wings.
HOW MORBIUS SETS UP THE SINISTER SIX
Spider-Man is referenced throughout the Morbius trailer, both in the "From the Studio Who Brought you Spider-Man: Homecoming..." advertising and the Spider-Man posters that can be seen in the background with the word "Murderer" written over it in an apparent reference to the ending of Spider-Man: Far From Home).
One character no one expected to see, however, is Michael Keaton's Vulture, who cameos in what appears to be a prison jumpsuit at the end of the trailer. When we last saw Adrian Toomes, he was being carted off to prison after being beaten by Spider-Man. He wears his Spider-Man: Homecoming prison uniform in the trailer, implying that, at some point, Michael Morbius might be going to that prison for some reason. There could also be a prison break after Morbius is captured and imprisoned that forces him to break free.
No matter how they meet, the scene still brings two of Spider-Man's more noteworthy villains together for the first time on the big screen.
COULD MORBIUS JOIN THE SINISTER SIX?
The Morbius trailer confirms that Sony's Spider-Man universe is adjacent, at least, to the MCU, which confirms that we will see future ties between the Disney and Sony Spider-Man films. And if Sony can now use villains who appeared first in the MCU, it's entirely possible that it could be to a team-up in a potential Sinister Six movie.
Since Spider-Man swang into Captain America: Civil War, Vulture, Shocker, Venom, Riot, the Tinkerer, a pre-Scorpion Mac Gargan Mysterio and a pre-Carnage Cletus Kasady have all appeared. And they'll soon be joined by Morbius, Loxias Crown and Shriek. Of those villains, Riot and Mysterio are apparently dead, but Mysterio, a master of illusion, could always have faked his death. Any one of these characters can, potentially, be involved with a Sinister Six film.
Sony has already confirmed that its developing potential films based on Madame Web, Nightwatch, Kraven the Hunter, Black Cat and Silver Sable, though these films are so far in various stages of development. While Kraven is the only one of those characters who has a real history in the Sinister Six, any of those potential movies could bring a few more Spider-Man villains into the mix. Furthermore, we still don't know who will appear in the third MCU Spider-Man film or where he'll show up again. Another Spider-Man villain like Doctor Octopus, the founder of the Sinister Six, appear in this future film.
It might be tempting to conclude that Sony will use the characters introduced Morbius and Venom 2 to rush towards a Sinister Six film. But with so many other films in development, it's unlikely that Sony will feel the need to jump straight to a Sinister Six crossover film. It's possible Vulture's apparent release or escape will tie into a reappearance in the third Spider-Man film or some later Spider-Man adjacent film.
While it's still not clear if Venom or Morbius might join up with the Sinister Six or if Vulture and Mysterio will get the chance to work together, Sony is steadily added pieces to Spider-Man's world that could add up to the Sinister Six.