Kitty Pryde
Another X-Men casting possibility, Kitty Pryde actually has a well-established prior relationship with Peter Parker in various Marvel Comics lore. The two have complementary combat skills, matching attitudes, and even dated each other for a brief time in the Ultimate universe.
It’s that more intimate relationship which makes Kitty Pryde such a fascinating casting possibility for Sadie Sink. Given the hard reset Peter’s life took at the end of No Way Home, it’s easier to imagine Peter meeting Kitty Pryde in his new life, striking up some kind of relationship with her, and exploring new possibilities as well as being properly introduced to the entire mutant community. Sink’s age and character oeuvre to date make her a seemingly perfect fit for Kitty Pryde, though it’s reasonable to wonder if Pryde is enough of a major name to secure one of those coveted “X-Men cameo spots” that Feige hinted at.
Mary Jane Watson
If you subscribe to the “Sadie Sink must play a red headed character in the MCU” philosophy (as many seem to do), then you must consider the Mary Jane Watson possibility.
Yes, casting Sadie Sink as MJ in Spider-Man 4 would seemingly require the use of multiverse shenanigans or a small army of convenient plot points. Then again, these are the Spider-Man MCU movies we’re talking about! Multiversal shenanigans and convenient plotting is the name of the game! However it may happen, it’s hard to deny that Sink is seemingly a good fit for the classic Mary Jane role. It would be intriguing to watch Peter explore a relationship with another Ms. Watson now that he and Zendaya’s Michelle Jones-Watson have softly been split by the events of the previous film. That said… two MJs? In this economy?
Gwen Stacy
When you hear that a notable actress has reportedly been cast in a major role in an upcoming Spider-Man movie, it’s only natural to think “Gwen Stacy.” The death of Gwen Stacy is one of the most pivotal moments in Peter’s life, though the narrative evolution of the recent Marvel Spider-Man movies made it highly unlikely that we’d ever see Stacy in an MCU film outside of, perhaps, a cameo or No Way Home’s throwaway reference to the character.
Nowadays though, things are a bit different. If Marvel is interested in giving fans a full Gwen Stacy storyline, they would pretty much have to take advantage of this unique time when Peter’s life has effectively been reset and he’s free to explore a variety of possibilities that would have previously seemed impossible. It’s a stretch, but Gwen Stacy true believers have renewed reason to hope.