The Amazing Spider-Man 3 was planned to focus on Venom since there's an deleted scene of the symbiote, but yeah, Sinister Six was about to happen. More precisally, the ending of The Amazing Spider-Man 2 is literally the start of Sinister Six, since Harry asks to the Hat Man to recruit six members for his group, formed by:
- Green Goblin(Harry also counts)
- Dr. Octopus
- Vulture
- Rhino
- Kraven
- Chameleon
But here's the thing. When Amazing Spider 1 and 2 was releasing, MCU was in it's prime and Sony Pictures wanted to copy their 'Cinematic Universe".
So when Sony Pictures suffered a hacker attack, several projects related to the Spider-Man universe were leaked....
- The Amazing Spider-Man 3
- The Amazing Spider-Man 4
- Venom solo Movie(before Tom Hardy)
- Carnage solo movie
- Black Cat solo movie
- Spider-Man 2099 solo movie
Crazy how after all this, we still got an Venom Trilogy, Morbius, Madame Web and Kraven movies...