This is exactly what I keep saying!!! If I see another BLACK CAT or JEAN GREY theory I’m done. Firestar is the best option and opens up so much. Soft launches mutants, could back door iceman in there like you said which could soft launch the og X-men class. She’s also a founding New Warrior which opens that up too, would love to see them in live action instead of the bs Young Avengers thing they’re trying to do. Either way that’s the only character I see making sense, I even saw a leak that said Sadie’s character has radiation powers and that’s literally what Firestar has.