It's hard to even fathom that there are other Marvel movies after Avengers 4 -- hell, even Avengers: Infinity War -- but the MCU isn't stopping anytime soon, and it's got to plan for the future. Spider-Man: Homecoming 2 (or whatever it will be called) will open Phase 4, and Marvel is hard at work developing the movie. As is customary, the sequel will introduce new characters from the comic books, and a rumored casting call was looking for a female character that raised some eyebrows.
Supposedly, Marvel is looking for a 20-something woman of European descent to play a character that is described as a "femme fatale." Most fans will jump to Black Cat or Silver Sable, but both of those characters are tied up in Sony's Silver & Black, which may or may not be connected to the MCU depending on who you ask on any given day. So, for now, we kind of have to exclude them. But there are plenty of other women in Spidey's life and while they may not all be a femme fatale, I'd still like to see one (or all!) of these six women appear in Homecoming 2.
Probably the most obvious choice after you remove Black Cat and Silver Sable from the equation. Jessica Drew aka Spider-Woman was a spy who was a double agent working for Hydra and then for S.H.I.E.L.D. That's got femme fatale all over it. Plus, she was born in Europe. She actually has almost nothing to do with Peter Parker, only somewhat recently being tied to his mythos. She just kind of took the Spider-Woman name because her powers were vaguely spider-y, but the MCU is certainly no stranger to reworking characters, so her backstory could always be changed. In the Ultimate universe, she was reimagined as being Peter Parker's female clone. Spider-Woman also has a history as an Avenger, so her inclusion is just a matter of time.
Yes, yes, we already got Gwen Stacy in The Amazing Spider-Man film series, but that's not going to stop Marvel from using one of the biggest Spider-Man characters ever and it's already rumored that she'll be appearing in the sequel. That just means they have to be a bit more creative to make her fresh. Maybe it's too soon, but we've already got a new version of Mary Jane (kind of), so why not add in Gwen, too? One way to do that is to make her more of a mysterious figure, like an exchange student with a secret to hide. Maybe fans wouldn't be too happy with such a change but if Gwen Stacy is going to be in these movies (and she will eventually) it's going to have to be different. We can't just see the same old thing we saw three years ago. Of course, there's always the Spider-Gwen option.
The Tom Holland Spider-Man hasn't gotten to the point where he needs to worry about the police, but when he does, let's hope Jean DeWolff will be there to greet him. While George Stacey might be the most prominent of Spidey's allies on the force, DeWolff is a close second. She was one of Spidey's most staunch defenders, believing that he was a benefit to the NYPD and not a menace. The two of them worked together on lots of cases before her untimely murder, something that has always weighed down on Spidey. DeWolff has never really gotten much exposure outside of the comics, so she would be a welcome new addition to the mainstream.
The rights for this one are tricky. Technically, Firestar is an X-Man, but she was created for the Spider-Man and his Amazing Friends cartoon, where she palled around with Spider-Man and Ice Man on various adventures as a superhero team; they were also roommates. She's arguably far more associated with Spider-Man than the X-Men, but the specifics of where her rights belong are unclear. Regardless, it hardly matters anymore thanks to Disney, but it's unlikely the rights go to Marvel in time for filming the Homecoming sequel. Marvel could use one of their legal loopholes to get Firestar in the sequel, much like they did with Scarlet Witch and Quicksilver once upon a time. We've never seen Spidey interact with heroes his own age before, and more romance options that aren't Mary Jane or Gwen aren't bad.
Madame Web is a psychic with the ability to see into the future and is distinctly web-themed, which means she mostly interacts with Spider-Man. She often allies herself with Spider-Man, giving him a warning of things to come, but not how he can avoid it. Usually, when she shows up, you know shit is going down. Madame Web would open up a whole new world for the MCU's Spider-Man, taping into the more mythic portions of his story that don't get much attention outside of the comics. Madame Web is typically depicted as an elderly woman, but Homecoming 2 could always opt to shake things up and use her successor, Julia Carpenter, the second Spider-Woman.
A more recent addition to Spider-Man's world, Cindy Moon was the second and only other person to be bitten by the same spider that gave Peter his powers. She was almost immediately locked away in a bomb shelter for, uh, reasons... until Spider-Man found out she existed and freed her. Cindy has most of the powers of Spider-Man, only she's faster and can shoot webs from her fingertips. She's grown to be fairly popular since her debut and she's got a great costume, so it only makes sense that she'd appear in a movie sooner or later. Tiffany Espensen is credited as playing a girl named Cindy in Homecoming, but she's never called Cindy Moon and she's mostly in the background, so it's unclear if Silk has technically already made her debut and Marvel is keeping it on the down low.