MCU devotees continue to debate over who will inherit Iron Man's legacy in the MCU, but Iron Man 3 already paved the way for Tony Stark's best successor. Iron Man casts a long, looming shadow over the MCU landscape, and will likely continue to do so for decades to come. That makes total sense, as Robert Downey Jr.'s snarky superhero was the first character to lead an MCU movie, and had the first Iron Man not taken off, it's possible the entire MCU experiment would've been doomed to fail.
If Marvel Studios had the option, it's not hard to imagine they would have kept Downey around for much longer, content to use his star power to continue to boost the MCU's fortunes to even greater heights. That wasn't in the cards though, as after a decade playing Tony Stark, Downey wanted out, leading to Iron Man's emotionally devastating ending at the conclusion of Avengers: Endgame. If Iron Man had to die, though, he couldn't have hoped to do it any better, going out surrounded by friends, and after saving the universe one last time.
Since Iron Man's demise, much time has been spent both in and out of the MCU debating who can possibly hope to fill the void he left behind and be his immediate successor. The most obvious candidate seems like Ironheart, the subject of an upcoming Disney+ show, but Spider-Man and Tony's own daughter Morgan also seem like possibilities. Yet, most aspects of this debate ignore the person who should be the most obvious choice to take over his work: Tony's wife Pepper Potts. Pepper has her own Iron Man-like Rescue super suit as seen in Endgame and knows how to use it, has access to all of Tony's resources and knowledge, and could even justifiably be revealed to have some form of powers as a result of her exposure to Extremis if the MCU wanted further justification for her taking on a superhero role.
To be fair, Pepper Potts would have a major obstacle to becoming a full-time superhero, much less an Avenger. With Tony gone, Pepper is now a widowed single mother, and raising her daughter Morgan would surely always come first. Still, that doesn't mean Pepper can't suit up in the Rescue armor when her help is needed, bringing Iron Man's signature tech back into the fray against supervillains. By doing so, Pepper would be doing both Morgan and Tony proud, and help directly carry on the Iron Man legacy of heroism.
Having Pepper serve as a stand-in of sorts for Iron Man would also prevent the character from being relegated only to the sidelines, after having experienced lots of character growth since the original Iron Man film. Pepper went from a character MCU viewers were mixed on, to a popular Marvel movie figure, which isn't worth throwing to one side entirely for the franchise. Ironheart and Peter Parker may help Iron Man's crusade survive for decades to come - presuming people eventually remember who Peter is - but for the near term, Pepper Potts is Tony Stark's best successor.
