I think that I speak the facts when I say that despite whatever one may think about Ms. Marvel or The Marvels, Iman Vellani was amazing in both. She was also great in Marvel Zombies. If you've seen the interviews, she's as much of a fan as the die-hards, and often times the interviews go into non-Ms. Marvel topics and it's amazing. She's a fan who cares, and personally, I think that's really important in a studio head. Look at James Gunn, he's a fan of these things, and that's one of the many reasons why the DCU is great. Feige didn't start out as a fan, but he made himself into one while working on X-Men, and that's one of the many reasons why the MCU worked.

Also, Vellani isn't even 25, assuming Feige steps down in like at most, twenty years, and seeing that Kathleen Kennedy is in her 70s and still the head of Star Wars, Vellani could do it for a long time. It's also important to note that it's unlikely that Vellani is like Dwayne 'the Rock' Johnson, and probably would not make her character the center of the universe, like Dwayne 'the Rock' Johnson tried to do with his failed coup of DC back in 2022.

tl;dr: Iman Vellani is great, and would probably make a great studio head.
Whenever Feige steps down, be it in ten years or twenty, Iman Vellani would make a great head of Marvel Studios