Spoilers ahead for Avengers: Endgame.
Phase Three of the Marvel Cinematic Universe has been on a serious roll. With the exception of BTS drama like James Gunn's firing, the current slate of movies has gone on without a hitch. Avengers: Endgame is very close to becoming the most profitable movie of all time, but it's surprisingly not the final installment in Phase Three. That honor goes to Spider-Man: Far From Home, which is mere days away from arriving in theaters-- including some new suits.
Spider-Man: Far From Home is Tom Holland's second solo movie, after appearing in a variety of movies throughout the recent phase of movies. While the public originally anticipated the movie being the first installment in Phase Four, it turns out it will be the conclusion to the Infinity Saga. Kevin Feige recently explained this decision, saying:
And as we were working on Endgame, we realized that the true end of the entire Infinity Saga, the final film of Phase 3, had to be Spider-Man: Far From Home, because – spoiler – we lose Tony Stark at the end of Endgame. And the relationship between Peter Parker and Tony Stark is so special over the five films that Tom Holland has portrayed Spider-Man in the MCU, that we needed to see where his journey went, and see how does Spider-Man step out of the shadow of his mentor Tony Stark and become the true hero that he was always meant to be. It's for that reason that Endgame and Spider-Man: Far From Home are essentially two pieces of the same story, and it's not over yet until Spider-Man: Far From Home.
It looks like Avengers: Endgame's final battle is what affected the decision to include Spider-Man: Far From Home as Phase Three's final movie. Tony Stark heroically sacrificed himself to destroy Thanos forever, and its a plot point that is sure to be felt throughout the entire MCU. Especially for Peter Parker, given his father/son dynamic with Iron Man.
Peter Parker and Tony Stark's mentor relationship was one of the new additions to Phase Three, beginning with Captain America: Civil War. It was really fleshed out in Spider-Man: Homecoming, as well as Avengers: Infinity War. Tony's true affection for Peter became relevant once he was faded away to dust, and the five years that followed before the Time Heist.
Kevin Feige's comments to Comic Book make total sense, given the marketing of Spider-Man: Far From Home. Peter's grief over Tony Stark's Endgame death seems to be at the front of the sequel's narrative. In addition to speaking with Happy Hogan and Jake Gyllenhaal's Mysterio about his loss, the imagery of Iron Man is shown literally looming above his head. Add in the use of the Iron Spider armor, and Iron Man is very much part of the fabric of the upcoming sequel.