The MCU could still create Iron Man 4 - but to honor Tony Stark's legacy, and to show his successors dealing with the fallout from his death.
Iron Man 4 may be a more fitting send-off to Tony Stark without him playing the role of the hero. Stark's death in Avengers: Endgame was tragic for several reasons; his self-sacrifice, the family and friends he left behind, and the fact it put an end to a character who could have continued in the MCU for countless years based on the comics alone.
Although Iron Man's role in the MCU did define Marvel's entire franchise - and had a series of engaging storylines that brought a sense of genuine character development along with them - many were surprised to see him go in Endgame, despite the fact that his trilogy of Iron Man films had seen him go through an arc that made it clear he was willing to give his life to save the world and those within in. While it could be argued that many didn't see this demise coming out of sentimental reasons, there is also a practical one: there are a ton of iconic Iron Man comics the MCU didn't touch, that could have been perfect for Iron Man 4. In fact, prior to this, it had been speculated for some time that Tony's plotline would culminate in an Armor Wars adaptation - only for it to instead be revealed that this comic would be used for a Disney+ series starring War Machine instead.
Marvel Is Doing Iron Man 4's Best Story Without Tony Stark
This raises the strange but satisfying concept, however, that there still could be an Iron Man 4. In fact, there should be an Iron Man 4, as it makes more sense to dedicate one film to the aftermath of Tony's death and the subsequent impact it has not only on the MCU roster but also the Marvel world - instead of solely showing it through things like Spider-Man: Far From Home's plot revolving around an AI named EDITH Tony leaves Peter in case of his death. While moments like this should still be included, there's surely far more to cover in regards to how the loss of Iron Man could affect Marvel's America and future, and making room for this to be fully explored through a fourth film dedicated to the hero may actually still be the best option.
For example, even if many considered him the villain of Captain America: Civil War, it's undeniable that the film showed audiences that Tony served as a peacekeeper between the superhero community and the government, attempting to balance out the desires and wants of both groups. Though always something of a loose cannon, the general public appears to have always rooted for Stark, much in the same way audiences did. Combine this with the fact he (along with the now also missing Captain America) led the Avengers themselves, and it's clear a lot of things need to be established and changed in the coming films and shows to breach the gap that Stark has left in the MCU.
Seeing how this void is filled by figures like War Machine and the MCU's new hero Ironheart - and how they honor the legacy of Iron Man - could be one of the most interesting parts of Phase 4. Though having an Iron Man 4 without Iron Man is a weird notion, it's also one that could ultimately serve as a fitting tribute.
