The Avengers 4 theory going around online suggesting that Pepper Potts might be the one to save Tony Stark from being trapped in Titan is not true. Thanos' galactic genocide in Avengers: Infinity War left only a handful of heroes alive, most of which had converged in Wakanda. While Thor, Captain America and the rest of the surviving characters can easily return to the kingdom and be accommodated by Shuri and Queen Ramonda as they try to make sense of what just happened, Tony was left stranded on Titan with Nebula. And without a functioning armor, many are wondering how he can return to Earth and finally join the team as they gear up for the ultimate battle against the Mad Titan in next year's still-untitled film.
Pepper didn't have a whole lot to do in Infinity War, but she had some key moments that will more likely have an impact on Tony's character arc moving forward. Having been engaged for two years before Thanos' invasion, the pair were talking about the idea of having a kid before Doctor Strange appeared and whisked Tony away to help with the incoming threat. But with where things left the film for the pioneering MCU hero, several theories as to how he can leave Titan float online, including a brand new one claiming that Pepper might be the one to rescue him. Sadly, it doesn't look like it will be the case.
Yahoo! Movies cites several Twitter posts implying that Pepper Potts may actually be the one to rescue Tony from Titan after she supposedly said, "I'm going too," during their last-minute conversation before he traveled to Titan. However, upon further listening to the phone call, it was actually Tony's AI, Friday, who said this, telling her boss that she won't be able to assist him as Ebony Maw's spaceship moved further from Earth. In fact, before bidding him goodbye, the AI even told him, "We're losing her," pertaining to the soon-to-drop connection between the couple. That means Pepper's last words to her fiancée were "Come back" as she persuaded him to drop his self-appointed mission.
Given this, it's safe to say that however Tony gets off Titan, chances are Pepper won't be the one to bring him back to Earth. While it's still unclear how he can leave the planet, there are a couple of ways that he can go about it. First, it's possible that the Guardians of the Galaxy's ship is still in the vicinity, which he can use as transport. Nebula's spacecraft didn't seem to be that damaged, so they can use that as well. Other theories also suggest that Captain Marvel, who is believed to be in outer space, might rescue him. Otherwise, considering Tony's brilliance, it's not outside the realm of possibility that he can build a brand new vessel from the materials that can be found on the planet.
Having said that, it doesn't mean Pepper won't have any significant arc in Avengers 4. Last year, Paltrow posted a set photo of her wearing a motion-capture suit while waiting for her turn in front of the camera. This gave people the impression that Pepper might don her own suit in the Phase 3 capper, although considering how paranoid Tony can be, it's possible that he just made a separate suit for her in case something happens and she needs protection.
Source: Yahoo! Movies