This summer's Spider-Man: Homecoming picks up in the aftermath of Captain America: Civil War, as a young Peter Parker (Tom Holland) struggles to readjust to his daily life as a teenaged superhero/high school sophomore. It remains to be seen exactly what the future holds for the web-slinger in the Marvel Cinematic Universe - but college life and/or a post-high school career (see: working as a photographer for The Daily Bugle), is one of the things that may not lie in the cards for Holland's Mr. Parker, on the big screen.
Holland himself has indicated before that any and all future Spider-Man: Homecoming sequels will follow "the Harry Potter formula", exploring one year in Peter's high school career per movie. With Homecoming following Peter through his various adventures as a tenth grader, that paves the way for a potential Homecoming film trilogy that is set entirely in high school, culminating with Peter's experience as a high school senior.
When Screen Rant visited the Spider-Man: Homecoming set last year, Holland was asked if each of the MCU-based Spider-Man films will take place during a year of Peter's high school run. Holland joked at first that "That’s the first time I’m hearing that!" before laughing and confirming that, from what he understands, that is the plan at the moment:
Tom Holland: No, I’m sure that is the formula they’re going to take. Peter is 15 in this movie, and that would make him in grade... ten?
Screen Rant: Yeap, grade 10.
Tom Holland: And yeah I see him graduating towards the last movie
The Spider-Man: Homecoming sequel release date is set for 2019, e.g. two years after Homecoming hits theaters and one year after Holland's web-slinger teams up with the MCU's other superheroes to battle Thanos, in 2018's Avengers: Infinity War. That could put Peter Parker in his senior year of high school in the second Homecoming movie, assuming that the sequel picks up in "real-time," as the MCU films in the past typically have. If that doesn't happen, then the third Homecoming installment would instead be the movie that picks up with Holland's web-slinger as a high school senior, with the second installment focusing on his antics as a junior, post-Infinity War.
Seeing as there's even some question as to whether Spider-Man will remain part of the MCU after the Homecoming sequel hits theaters, it's too early to assume that anything's been set in stone, regarding a potential third Homecoming film. With that in mind, both the Sam Raimi-helmed Spider-Man trilogy and Marc Webb's The Amazing Spider-Man 1&2 explored Peter's life after high school - meaning, a Homecoming trilogy set entirely before Peter graduates from 12th grade would be a change of pace (and, possibly, a fresh approach), from previous iterations of the franchise.
