Baby Yoda was Avengers: Endgame. While she didn't have much screen time in the 2019 Joe and Anthony Russo film, she immediately became a fan-favorite thanks to her wit that's reminiscent of her dad.
Jedi Master Yoda was introduced. Since then, much of the narrative of the show revolved around Mando attempting to keep the infant safe; by season 2, he was tasked to reunite him with the Jedi. Despite the significant change in its course, it ultimately paid off with Baby Yoda, whose real name is Grogu, being the most popular element of the project.
The MCU is already an established brand and certainly more stable than Star Wars following the sequel trilogy, but that doesn't mean that it's not looking for ways to elevate its popularity. Marvel Studios has a full slate for Phase 4, but if they're wanting to take a page from Lucasfilm's books, they could utilize Morgan as their version of Baby Yoda. On the surface, they don't seem to have any similarities other than being adorable; but, there's more to it than that. When Grogu was introduced, he looked like an incapable infant that needed protection; as The Mandalorian progressed, however, it became clear that he's more capable than he lets on. Multiple times in the show thus far, he has saved Din and his other friends through his use of the Force.
Marvel Studios can do this to Morgan as well. With her parents both smart and capable, the young Stark can very well exceed expectations for a child her age. In Endgame, it was already revealed that she's aware of her father's superhero identity and she's interested in learning more by taking the Rescue armor headpiece and wearing it as if it's her own. Depending on how Marvel Studios wants to progress her character past the Infinity Saga, it's not impossible to think Morgan could have a bigger role in the MCU. She could pilot one of Stark's creations, perhaps even take on the mantle of Rescue in the MCU; better yet, she can build something else using Stark Tech. This would make her a dangerous foe despite her young age.
Granted that there are other adorable characters in the MCU, a notable one that always gets compared to Baby Yoda is Baby Groot, but at this point, the sentient tree creature is already a teenager. If there are no plans of introducing another variant of the character, he will continue to grow older and wouldn't have the same appeal as The Mandalorian's Grogu. Meanwhile, they still have time to develop Iron Man's daughter to be an integral player in the franchise.
